content/ppapi_plugin/ppapi_thread.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/ppapi_plugin/ppapi_thread.h"
   6
   7 #include <limits>
   8
   9 #include "base/command_line.h"
  10 #include "base/cpu.h"
  11 #include "base/debug/crash_logging.h"
  12 #include "base/files/file_util.h"
  13 #include "base/logging.h"
  14 #include "base/memory/discardable_memory_allocator.h"
  15 #include "base/metrics/histogram.h"
  16 #include "base/metrics/sparse_histogram.h"
  17 #include "base/rand_util.h"
  18 #include "base/strings/stringprintf.h"
  19 #include "base/strings/utf_string_conversions.h"
  20 #include "base/threading/platform_thread.h"
  21 #include "base/time/time.h"
  22 #include "content/child/browser_font_resource_trusted.h"
  23 #include "content/child/child_discardable_shared_memory_manager.h"
  24 #include "content/child/child_process.h"
  25 #include "content/common/child_process_messages.h"
  26 #include "content/common/sandbox_util.h"
  27 #include "content/ppapi_plugin/broker_process_dispatcher.h"
  28 #include "content/ppapi_plugin/plugin_process_dispatcher.h"
  29 #include "content/ppapi_plugin/ppapi_blink_platform_impl.h"
  30 #include "content/public/common/content_client.h"
  31 #include "content/public/common/content_switches.h"
  32 #include "content/public/common/pepper_plugin_info.h"
  33 #include "content/public/common/sandbox_init.h"
  34 #include "content/public/plugin/content_plugin_client.h"
  35 #include "ipc/ipc_channel_handle.h"
  36 #include "ipc/ipc_platform_file.h"
  37 #include "ipc/ipc_sync_channel.h"
  38 #include "ipc/ipc_sync_message_filter.h"
  39 #include "ppapi/c/dev/ppp_network_state_dev.h"
  40 #include "ppapi/c/pp_errors.h"
  41 #include "ppapi/c/ppp.h"
  42 #include "ppapi/proxy/interface_list.h"
  43 #include "ppapi/proxy/plugin_globals.h"
  44 #include "ppapi/proxy/plugin_message_filter.h"
  45 #include "ppapi/proxy/ppapi_messages.h"
  46 #include "ppapi/proxy/resource_reply_thread_registrar.h"
  47 #include "third_party/WebKit/public/web/WebKit.h"
  48 #include "ui/base/ui_base_switches.h"
  49
  50 #if defined(OS_WIN)
  51 #include "base/win/win_util.h"
  52 #include "base/win/windows_version.h"
  53 #include "sandbox/win/src/sandbox.h"
  54 #elif defined(OS_MACOSX)
  55 #include "content/common/sandbox_init_mac.h"
  56 #endif
  57
  58 #if defined(OS_WIN)
  59 const char kWidevineCdmAdapterFileName[] = "widevinecdmadapter.dll";
  60
  61 extern sandbox::TargetServices* g_target_services;
  62
  63 // Used by EnumSystemLocales for warming up.
  64 static BOOL CALLBACK EnumLocalesProc(LPTSTR lpLocaleString) {
  65   return TRUE;
  66 }
  67
  68 static BOOL CALLBACK EnumLocalesProcEx(
  69     LPWSTR lpLocaleString,
  70     DWORD dwFlags,
  71     LPARAM lParam) {
  72   return TRUE;
  73 }
  74
  75 // Warm up language subsystems before the sandbox is turned on.
  76 static void WarmupWindowsLocales(const ppapi::PpapiPermissions& permissions) {
  77   ::GetUserDefaultLangID();
  78   ::GetUserDefaultLCID();
  79
  80   if (permissions.HasPermission(ppapi::PERMISSION_FLASH)) {
  81     if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
  82       typedef BOOL (WINAPI *PfnEnumSystemLocalesEx)
  83           (LOCALE_ENUMPROCEX, DWORD, LPARAM, LPVOID);
  84
  85       HMODULE handle_kern32 = GetModuleHandleW(L"Kernel32.dll");
  86       PfnEnumSystemLocalesEx enum_sys_locales_ex =
  87           reinterpret_cast<PfnEnumSystemLocalesEx>
  88               (GetProcAddress(handle_kern32, "EnumSystemLocalesEx"));
  89
  90       enum_sys_locales_ex(EnumLocalesProcEx, LOCALE_WINDOWS, 0, 0);
  91     } else {
  92       EnumSystemLocalesW(EnumLocalesProc, LCID_INSTALLED);
  93     }
  94   }
  95 }
  96
  97 #endif
  98
  99 namespace content {
 100
 101 typedef int32_t (*InitializeBrokerFunc)
 102     (PP_ConnectInstance_Func* connect_instance_func);
 103
 104 PpapiThread::PpapiThread(const base::CommandLine& command_line, bool is_broker)
 105     : is_broker_(is_broker),
 106       plugin_globals_(GetIOTaskRunner()),
 107       connect_instance_func_(NULL),
 108       local_pp_module_(base::RandInt(0, std::numeric_limits<PP_Module>::max())),
 109       next_plugin_dispatcher_id_(1) {
 110   plugin_globals_.SetPluginProxyDelegate(this);
 111   plugin_globals_.set_command_line(
 112       command_line.GetSwitchValueASCII(switches::kPpapiFlashArgs));
 113
 114   blink_platform_impl_.reset(new PpapiBlinkPlatformImpl);
 115   blink::initialize(blink_platform_impl_.get());
 116
 117   if (!is_broker_) {
 118     scoped_refptr<ppapi::proxy::PluginMessageFilter> plugin_filter(
 119         new ppapi::proxy::PluginMessageFilter(
 120             NULL, plugin_globals_.resource_reply_thread_registrar()));
 121     channel()->AddFilter(plugin_filter.get());
 122     plugin_globals_.RegisterResourceMessageFilters(plugin_filter.get());
 123   }
 124
 125   // In single process, browser main loop set up the discardable memory
 126   // allocator.
 127   if (!command_line.HasSwitch(switches::kSingleProcess)) {
 128     base::DiscardableMemoryAllocator::SetInstance(
 129         ChildThreadImpl::discardable_shared_memory_manager());
 130   }
 131 }
 132
 133 PpapiThread::~PpapiThread() {
 134 }
 135
 136 void PpapiThread::Shutdown() {
 137   ChildThreadImpl::Shutdown();
 138
 139   ppapi::proxy::PluginGlobals::Get()->ResetPluginProxyDelegate();
 140   if (plugin_entry_points_.shutdown_module)
 141     plugin_entry_points_.shutdown_module();
 142   blink_platform_impl_->Shutdown();
 143   blink::shutdown();
 144 }
 145
 146 bool PpapiThread::Send(IPC::Message* msg) {
 147   // Allow access from multiple threads.
 148   if (base::MessageLoop::current() == message_loop())
 149     return ChildThreadImpl::Send(msg);
 150
 151   return sync_message_filter()->Send(msg);
 152 }
 153
 154 // Note that this function is called only for messages from the channel to the
 155 // browser process. Messages from the renderer process are sent via a different
 156 // channel that ends up at Dispatcher::OnMessageReceived.
 157 bool PpapiThread::OnControlMessageReceived(const IPC::Message& msg) {
 158   bool handled = true;
 159   IPC_BEGIN_MESSAGE_MAP(PpapiThread, msg)
 160     IPC_MESSAGE_HANDLER(PpapiMsg_LoadPlugin, OnLoadPlugin)
 161     IPC_MESSAGE_HANDLER(PpapiMsg_CreateChannel, OnCreateChannel)
 162     IPC_MESSAGE_HANDLER(PpapiMsg_SetNetworkState, OnSetNetworkState)
 163     IPC_MESSAGE_HANDLER(PpapiMsg_Crash, OnCrash)
 164     IPC_MESSAGE_HANDLER(PpapiMsg_Hang, OnHang)
 165     IPC_MESSAGE_UNHANDLED(handled = false)
 166   IPC_END_MESSAGE_MAP()
 167   return handled;
 168 }
 169
 170 void PpapiThread::OnChannelConnected(int32 peer_pid) {
 171   ChildThreadImpl::OnChannelConnected(peer_pid);
 172 #if defined(OS_WIN)
 173   if (is_broker_)
 174     peer_handle_.Set(::OpenProcess(PROCESS_DUP_HANDLE, FALSE, peer_pid));
 175 #endif
 176 }
 177
 178 base::MessageLoopProxy* PpapiThread::GetIPCMessageLoop() {
 179   return ChildProcess::current()->io_message_loop_proxy();
 180 }
 181
 182 base::WaitableEvent* PpapiThread::GetShutdownEvent() {
 183   return ChildProcess::current()->GetShutDownEvent();
 184 }
 185
 186 IPC::PlatformFileForTransit PpapiThread::ShareHandleWithRemote(
 187     base::PlatformFile handle,
 188     base::ProcessId peer_pid,
 189     bool should_close_source) {
 190 #if defined(OS_WIN)
 191   if (peer_handle_.IsValid()) {
 192     DCHECK(is_broker_);
 193     return IPC::GetFileHandleForProcess(handle, peer_handle_.Get(),
 194                                         should_close_source);
 195   }
 196 #endif
 197
 198   DCHECK(peer_pid != base::kNullProcessId);
 199   return BrokerGetFileHandleForProcess(handle, peer_pid, should_close_source);
 200 }
 201
 202 std::set<PP_Instance>* PpapiThread::GetGloballySeenInstanceIDSet() {
 203   return &globally_seen_instance_ids_;
 204 }
 205
 206 IPC::Sender* PpapiThread::GetBrowserSender() {
 207   return this;
 208 }
 209
 210 std::string PpapiThread::GetUILanguage() {
 211   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
 212   return command_line->GetSwitchValueASCII(switches::kLang);
 213 }
 214
 215 void PpapiThread::PreCacheFont(const void* logfontw) {
 216 #if defined(OS_WIN)
 217   ChildThreadImpl::PreCacheFont(*static_cast<const LOGFONTW*>(logfontw));
 218 #endif
 219 }
 220
 221 void PpapiThread::SetActiveURL(const std::string& url) {
 222   GetContentClient()->SetActiveURL(GURL(url));
 223 }
 224
 225 PP_Resource PpapiThread::CreateBrowserFont(
 226     ppapi::proxy::Connection connection,
 227     PP_Instance instance,
 228     const PP_BrowserFont_Trusted_Description& desc,
 229     const ppapi::Preferences& prefs) {
 230   if (!BrowserFontResource_Trusted::IsPPFontDescriptionValid(desc))
 231     return 0;
 232   return (new BrowserFontResource_Trusted(
 233         connection, instance, desc, prefs))->GetReference();
 234 }
 235
 236 uint32 PpapiThread::Register(ppapi::proxy::PluginDispatcher* plugin_dispatcher) {
 237   if (!plugin_dispatcher ||
 238       plugin_dispatchers_.size() >= std::numeric_limits<uint32>::max()) {
 239     return 0;
 240   }
 241
 242   uint32 id = 0;
 243   do {
 244     // Although it is unlikely, make sure that we won't cause any trouble when
 245     // the counter overflows.
 246     id = next_plugin_dispatcher_id_++;
 247   } while (id == 0 ||
 248            plugin_dispatchers_.find(id) != plugin_dispatchers_.end());
 249   plugin_dispatchers_[id] = plugin_dispatcher;
 250   return id;
 251 }
 252
 253 void PpapiThread::Unregister(uint32 plugin_dispatcher_id) {
 254   plugin_dispatchers_.erase(plugin_dispatcher_id);
 255 }
 256
 257 void PpapiThread::OnLoadPlugin(const base::FilePath& path,
 258                                const ppapi::PpapiPermissions& permissions) {
 259   // In case of crashes, the crash dump doesn't indicate which plugin
 260   // it came from.
 261   base::debug::SetCrashKeyValue("ppapi_path", path.MaybeAsASCII());
 262
 263   SavePluginName(path);
 264
 265   // This must be set before calling into the plugin so it can get the
 266   // interfaces it has permission for.
 267   ppapi::proxy::InterfaceList::SetProcessGlobalPermissions(permissions);
 268   permissions_ = permissions;
 269
 270   // Trusted Pepper plugins may be "internal", i.e. built-in to the browser
 271   // binary.  If we're being asked to load such a plugin (e.g. the Chromoting
 272   // client) then fetch the entry points from the embedder, rather than a DLL.
 273   std::vector<PepperPluginInfo> plugins;
 274   GetContentClient()->AddPepperPlugins(&plugins);
 275   for (size_t i = 0; i < plugins.size(); ++i) {
 276     if (plugins[i].is_internal && plugins[i].path == path) {
 277       // An internal plugin is being loaded, so fetch the entry points.
 278       plugin_entry_points_ = plugins[i].internal_entry_points;
 279     }
 280   }
 281
 282   // If the plugin isn't internal then load it from |path|.
 283   base::ScopedNativeLibrary library;
 284   if (plugin_entry_points_.initialize_module == NULL) {
 285     // Load the plugin from the specified library.
 286     base::NativeLibraryLoadError error;
 287     library.Reset(base::LoadNativeLibrary(path, &error));
 288     if (!library.is_valid()) {
 289       LOG(ERROR) << "Failed to load Pepper module from " << path.value()
 290                  << " (error: " << error.ToString() << ")";
 291       if (!base::PathExists(path)) {
 292         ReportLoadResult(path, FILE_MISSING);
 293         return;
 294       }
 295       ReportLoadResult(path, LOAD_FAILED);
 296       // Report detailed reason for load failure.
 297       ReportLoadErrorCode(path, error);
 298       return;
 299     }
 300
 301     // Get the GetInterface function (required).
 302     plugin_entry_points_.get_interface =
 303         reinterpret_cast<PP_GetInterface_Func>(
 304             library.GetFunctionPointer("PPP_GetInterface"));
 305     if (!plugin_entry_points_.get_interface) {
 306       LOG(WARNING) << "No PPP_GetInterface in plugin library";
 307       ReportLoadResult(path, ENTRY_POINT_MISSING);
 308       return;
 309     }
 310
 311     // The ShutdownModule/ShutdownBroker function is optional.
 312     plugin_entry_points_.shutdown_module =
 313         is_broker_ ?
 314         reinterpret_cast<PP_ShutdownModule_Func>(
 315             library.GetFunctionPointer("PPP_ShutdownBroker")) :
 316         reinterpret_cast<PP_ShutdownModule_Func>(
 317             library.GetFunctionPointer("PPP_ShutdownModule"));
 318
 319     if (!is_broker_) {
 320       // Get the InitializeModule function (required for non-broker code).
 321       plugin_entry_points_.initialize_module =
 322           reinterpret_cast<PP_InitializeModule_Func>(
 323               library.GetFunctionPointer("PPP_InitializeModule"));
 324       if (!plugin_entry_points_.initialize_module) {
 325         LOG(WARNING) << "No PPP_InitializeModule in plugin library";
 326         ReportLoadResult(path, ENTRY_POINT_MISSING);
 327         return;
 328       }
 329     }
 330   }
 331
 332 #if defined(OS_WIN)
 333   // If code subsequently tries to exit using abort(), force a crash (since
 334   // otherwise these would be silent terminations and fly under the radar).
 335   base::win::SetAbortBehaviorForCrashReporting();
 336
 337   // Once we lower the token the sandbox is locked down and no new modules
 338   // can be loaded. TODO(cpu): consider changing to the loading style of
 339   // regular plugins.
 340   if (g_target_services) {
 341     // Let Flash and Widevine CDM adapter load DXVA before lockdown on Vista+.
 342     if (permissions.HasPermission(ppapi::PERMISSION_FLASH) ||
 343         path.BaseName().MaybeAsASCII() == kWidevineCdmAdapterFileName) {
 344       if (base::win::OSInfo::GetInstance()->version() >=
 345           base::win::VERSION_VISTA) {
 346         LoadLibraryA("dxva2.dll");
 347       }
 348     }
 349
 350     if (permissions.HasPermission(ppapi::PERMISSION_FLASH)) {
 351       if (base::win::OSInfo::GetInstance()->version() >=
 352           base::win::VERSION_WIN7) {
 353         base::CPU cpu;
 354         if (cpu.vendor_name() == "AuthenticAMD") {
 355           // The AMD crypto acceleration is only AMD Bulldozer and above.
 356 #if defined(_WIN64)
 357           LoadLibraryA("amdhcp64.dll");
 358 #else
 359           LoadLibraryA("amdhcp32.dll");
 360 #endif
 361         }
 362       }
 363     }
 364
 365     // Cause advapi32 to load before the sandbox is turned on.
 366     unsigned int dummy_rand;
 367     rand_s(&dummy_rand);
 368
 369     WarmupWindowsLocales(permissions);
 370
 371 #if defined(ADDRESS_SANITIZER)
 372     // Bind and leak dbghelp.dll before the token is lowered, otherwise
 373     // AddressSanitizer will crash when trying to symbolize a report.
 374     LoadLibraryA("dbghelp.dll");
 375 #endif
 376
 377     g_target_services->LowerToken();
 378   }
 379 #endif
 380
 381   if (is_broker_) {
 382     // Get the InitializeBroker function (required).
 383     InitializeBrokerFunc init_broker =
 384         reinterpret_cast<InitializeBrokerFunc>(
 385             library.GetFunctionPointer("PPP_InitializeBroker"));
 386     if (!init_broker) {
 387       LOG(WARNING) << "No PPP_InitializeBroker in plugin library";
 388       ReportLoadResult(path, ENTRY_POINT_MISSING);
 389       return;
 390     }
 391
 392     int32_t init_error = init_broker(&connect_instance_func_);
 393     if (init_error != PP_OK) {
 394       LOG(WARNING) << "InitBroker failed with error " << init_error;
 395       ReportLoadResult(path, INIT_FAILED);
 396       return;
 397     }
 398     if (!connect_instance_func_) {
 399       LOG(WARNING) << "InitBroker did not provide PP_ConnectInstance_Func";
 400       ReportLoadResult(path, INIT_FAILED);
 401       return;
 402     }
 403   } else {
 404 #if defined(OS_MACOSX)
 405     // We need to do this after getting |PPP_GetInterface()| (or presumably
 406     // doing something nontrivial with the library), else the sandbox
 407     // intercedes.
 408     CHECK(InitializeSandbox());
 409 #endif
 410
 411     int32_t init_error = plugin_entry_points_.initialize_module(
 412         local_pp_module_,
 413         &ppapi::proxy::PluginDispatcher::GetBrowserInterface);
 414     if (init_error != PP_OK) {
 415       LOG(WARNING) << "InitModule failed with error " << init_error;
 416       ReportLoadResult(path, INIT_FAILED);
 417       return;
 418     }
 419   }
 420
 421   // Initialization succeeded, so keep the plugin DLL loaded.
 422   library_.Reset(library.Release());
 423
 424   ReportLoadResult(path, LOAD_SUCCESS);
 425 }
 426
 427 void PpapiThread::OnCreateChannel(base::ProcessId renderer_pid,
 428                                   int renderer_child_id,
 429                                   bool incognito) {
 430   IPC::ChannelHandle channel_handle;
 431
 432   if (!plugin_entry_points_.get_interface ||  // Plugin couldn't be loaded.
 433       !SetupRendererChannel(renderer_pid, renderer_child_id, incognito,
 434                             &channel_handle)) {
 435     Send(new PpapiHostMsg_ChannelCreated(IPC::ChannelHandle()));
 436     return;
 437   }
 438
 439   Send(new PpapiHostMsg_ChannelCreated(channel_handle));
 440 }
 441
 442 void PpapiThread::OnSetNetworkState(bool online) {
 443   // Note the browser-process side shouldn't send us these messages in the
 444   // first unless the plugin has dev permissions, so we don't need to check
 445   // again here. We don't want random plugins depending on this dev interface.
 446   if (!plugin_entry_points_.get_interface)
 447     return;
 448   const PPP_NetworkState_Dev* ns = static_cast<const PPP_NetworkState_Dev*>(
 449       plugin_entry_points_.get_interface(PPP_NETWORK_STATE_DEV_INTERFACE));
 450   if (ns)
 451     ns->SetOnLine(PP_FromBool(online));
 452 }
 453
 454 void PpapiThread::OnCrash() {
 455   // Intentionally crash upon the request of the browser.
 456   volatile int* null_pointer = NULL;
 457   *null_pointer = 0;
 458 }
 459
 460 void PpapiThread::OnHang() {
 461   // Intentionally hang upon the request of the browser.
 462   for (;;)
 463     base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(1));
 464 }
 465
 466 bool PpapiThread::SetupRendererChannel(base::ProcessId renderer_pid,
 467                                        int renderer_child_id,
 468                                        bool incognito,
 469                                        IPC::ChannelHandle* handle) {
 470   DCHECK(is_broker_ == (connect_instance_func_ != NULL));
 471   IPC::ChannelHandle plugin_handle;
 472   plugin_handle.name = IPC::Channel::GenerateVerifiedChannelID(
 473       base::StringPrintf(
 474           "%d.r%d", base::GetCurrentProcId(), renderer_child_id));
 475
 476   ppapi::proxy::ProxyChannel* dispatcher = NULL;
 477   bool init_result = false;
 478   if (is_broker_) {
 479     BrokerProcessDispatcher* broker_dispatcher =
 480         new BrokerProcessDispatcher(plugin_entry_points_.get_interface,
 481                                     connect_instance_func_);
 482     init_result = broker_dispatcher->InitBrokerWithChannel(this,
 483                                                            renderer_pid,
 484                                                            plugin_handle,
 485                                                            false);
 486     dispatcher = broker_dispatcher;
 487   } else {
 488     PluginProcessDispatcher* plugin_dispatcher =
 489         new PluginProcessDispatcher(plugin_entry_points_.get_interface,
 490                                     permissions_,
 491                                     incognito);
 492     init_result = plugin_dispatcher->InitPluginWithChannel(this,
 493                                                            renderer_pid,
 494                                                            plugin_handle,
 495                                                            false);
 496     dispatcher = plugin_dispatcher;
 497   }
 498
 499   if (!init_result) {
 500     delete dispatcher;
 501     return false;
 502   }
 503
 504   handle->name = plugin_handle.name;
 505 #if defined(OS_POSIX)
 506   // On POSIX, transfer ownership of the renderer-side (client) FD.
 507   // This ensures this process will be notified when it is closed even if a
 508   // connection is not established.
 509   handle->socket = base::FileDescriptor(dispatcher->TakeRendererFD());
 510   if (handle->socket.fd == -1)
 511     return false;
 512 #endif
 513
 514   // From here, the dispatcher will manage its own lifetime according to the
 515   // lifetime of the attached channel.
 516   return true;
 517 }
 518
 519 void PpapiThread::SavePluginName(const base::FilePath& path) {
 520   ppapi::proxy::PluginGlobals::Get()->set_plugin_name(
 521       path.BaseName().AsUTF8Unsafe());
 522
 523   // plugin() is NULL when in-process, which is fine, because this is
 524   // just a hook for setting the process name.
 525   if (GetContentClient()->plugin()) {
 526     GetContentClient()->plugin()->PluginProcessStarted(
 527         path.BaseName().RemoveExtension().LossyDisplayName());
 528   }
 529 }
 530
 531 void PpapiThread::ReportLoadResult(const base::FilePath& path,
 532                                    LoadResult result) {
 533   DCHECK_LT(result, LOAD_RESULT_MAX);
 534   std::string histogram_name = std::string("Plugin.Ppapi") +
 535                                (is_broker_ ? "Broker" : "Plugin") +
 536                                "LoadResult_" + path.BaseName().MaybeAsASCII();
 537
 538   // Note: This leaks memory, which is expected behavior.
 539   base::HistogramBase* histogram =
 540       base::LinearHistogram::FactoryGet(
 541           histogram_name,
 542           1,
 543           LOAD_RESULT_MAX,
 544           LOAD_RESULT_MAX + 1,
 545           base::HistogramBase::kUmaTargetedHistogramFlag);
 546
 547   histogram->Add(result);
 548 }
 549
 550 void PpapiThread::ReportLoadErrorCode(
 551     const base::FilePath& path,
 552     const base::NativeLibraryLoadError& error) {
 553 #if defined(OS_WIN)
 554   // Only report load error code on Windows because that's the only platform
 555   // that has a numerical error value.
 556   std::string histogram_name =
 557       std::string("Plugin.Ppapi") + (is_broker_ ? "Broker" : "Plugin") +
 558       "LoadErrorCode_" + path.BaseName().MaybeAsASCII();
 559
 560   // For sparse histograms, we can use the macro, as it does not incorporate a
 561   // static.
 562   UMA_HISTOGRAM_SPARSE_SLOWLY(histogram_name, error.code);
 563 #endif
 564 }
 565
 566 }  // namespace content