chrome/browser/sessions/tab_loader_delegate.cc

   1 // Copyright 2014 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 "chrome/browser/sessions/tab_loader_delegate.h"
   6
   7 #include "base/strings/string_number_conversions.h"
   8 #include "components/variations/variations_associated_data.h"
   9 #include "net/base/network_change_notifier.h"
  10
  11 namespace {
  12
  13 // The timeout time after which the next tab gets loaded if the previous tab did
  14 // not finish loading yet. The used value is half of the median value of all
  15 // ChromeOS devices loading the 25 most common web pages. Half is chosen since
  16 // the loading time is a mix of server response and data bandwidth.
  17 static const int kInitialDelayTimerMS = 1500;
  18
  19 class TabLoaderDelegateImpl
  20     : public TabLoaderDelegate,
  21       public net::NetworkChangeNotifier::ConnectionTypeObserver {
  22  public:
  23   explicit TabLoaderDelegateImpl(TabLoaderCallback* callback);
  24   ~TabLoaderDelegateImpl() override;
  25
  26   // TabLoaderDelegate:
  27   base::TimeDelta GetFirstTabLoadingTimeout() const override {
  28     return first_timeout_;
  29   }
  30
  31   // TabLoaderDelegate:
  32   base::TimeDelta GetTimeoutBeforeLoadingNextTab() const override {
  33     return timeout_;
  34   }
  35
  36   // net::NetworkChangeNotifier::ConnectionTypeObserver:
  37   void OnConnectionTypeChanged(
  38       net::NetworkChangeNotifier::ConnectionType type) override;
  39
  40  private:
  41   // The function to call when the connection type changes.
  42   TabLoaderCallback* callback_;
  43
  44   // The timeouts to use in tab loading.
  45   base::TimeDelta first_timeout_;
  46   base::TimeDelta timeout_;
  47
  48   DISALLOW_COPY_AND_ASSIGN(TabLoaderDelegateImpl);
  49 };
  50
  51 TabLoaderDelegateImpl::TabLoaderDelegateImpl(TabLoaderCallback* callback)
  52     : callback_(callback) {
  53   net::NetworkChangeNotifier::AddConnectionTypeObserver(this);
  54   if (net::NetworkChangeNotifier::IsOffline()) {
  55     // When we are off-line we do not allow loading of tabs, since each of
  56     // these tabs would start loading simultaneously when going online.
  57     // TODO(skuhne): Once we get a higher level resource control logic which
  58     // distributes network access, we can remove this.
  59     callback->SetTabLoadingEnabled(false);
  60   }
  61
  62   // Initialize the timeouts to use from the session restore field trial.
  63   // Default to the usual value if none is specified.
  64
  65   static const char kIntelligentSessionRestore[] = "IntelligentSessionRestore";
  66   std::string timeout = variations::GetVariationParamValue(
  67       kIntelligentSessionRestore, "FirstTabLoadTimeoutMs");
  68   int timeout_ms = 0;
  69   if (timeout.empty() || !base::StringToInt(timeout, &timeout_ms) ||
  70       timeout_ms <= 0) {
  71     timeout_ms = kInitialDelayTimerMS;
  72   }
  73   first_timeout_ = base::TimeDelta::FromMilliseconds(timeout_ms);
  74
  75   timeout = variations::GetVariationParamValue(
  76       kIntelligentSessionRestore, "TabLoadTimeoutMs");
  77   timeout_ms = 0;
  78   if (timeout.empty() || !base::StringToInt(timeout, &timeout_ms) ||
  79       timeout_ms <= 0) {
  80     timeout_ms = kInitialDelayTimerMS;
  81   }
  82   timeout_ = base::TimeDelta::FromMilliseconds(timeout_ms);
  83 }
  84
  85 TabLoaderDelegateImpl::~TabLoaderDelegateImpl() {
  86   net::NetworkChangeNotifier::RemoveConnectionTypeObserver(this);
  87 }
  88
  89 void TabLoaderDelegateImpl::OnConnectionTypeChanged(
  90     net::NetworkChangeNotifier::ConnectionType type) {
  91   callback_->SetTabLoadingEnabled(
  92       type != net::NetworkChangeNotifier::CONNECTION_NONE);
  93 }
  94 }  // namespace
  95
  96 // static
  97 scoped_ptr<TabLoaderDelegate> TabLoaderDelegate::Create(
  98     TabLoaderCallback* callback) {
  99   return scoped_ptr<TabLoaderDelegate>(
 100       new TabLoaderDelegateImpl(callback));
 101 }