From 1f89c007ba4f55f8b386a49d9824029e6bca963b Mon Sep 17 00:00:00 2001
From: ccameron <ccameron@chromium.org>
Date: Mon, 20 Oct 2014 23:19:05 -0700
Subject: [PATCH] Add a flag to enable impl-thread event handling on Mac

This feature is in active development.

BUG=224781

Review URL: https://codereview.chromium.org/671533003

Cr-Commit-Position: refs/heads/master@{#300427}
---
 .../renderer_host/render_process_host_impl.cc      |  3 +++
 content/public/common/content_switches.cc          |  7 +++++-
 content/public/common/content_switches.h           |  1 +
 content/renderer/render_view_impl.cc               | 25 ++++++++++++++--------
 4 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index ff3f2b7a82c5..c8dd34bf73c1 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1238,6 +1238,9 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     // Allow this to be set when invoking the browser and relayed along.
     switches::kEnableSandboxLogging,
 #endif
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+    switches::kEnableThreadedEventHandlingMac,
+#endif
 #if defined(OS_WIN)
     switches::kDisableDirectWrite,
 #endif
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 791cc70e29e8..1b95179dbd86 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -940,9 +940,14 @@ const char kEnableSpeechDispatcher[] = "enable-speech-dispatcher";
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 // Disables support for Core Animation plugins. This is triggered when
-// accelerated compositing is disabled. See http://crbug.com/122430 .
+// accelerated compositing is disabled. See http://crbug.com/122430.
 const char kDisableCoreAnimationPlugins[] =
     "disable-core-animation-plugins";
+
+// Allows input events to be handed on the compositor thread.
+// This feature is under development, see http://crbug.com/138003.
+extern const char kEnableThreadedEventHandlingMac[] =
+    "enable-threaded-event-handling-mac";
 #endif
 
 #if defined(OS_WIN)
diff --git a/content/public/common/content_switches.h b/content/public/common/content_switches.h
index 9da3c1d4a69f..9ff824535018 100644
--- a/content/public/common/content_switches.h
+++ b/content/public/common/content_switches.h
@@ -276,6 +276,7 @@ CONTENT_EXPORT extern const char kEnableSpeechDispatcher[];
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 extern const char kDisableCoreAnimationPlugins[];
+extern const char kEnableThreadedEventHandlingMac[];
 #endif
 
 #if defined(OS_WIN)
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index d5ace2b06327..04edbd02faf3 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -2134,16 +2134,23 @@ void RenderViewImpl::initializeLayerTreeView() {
   if (webview() && webview()->devToolsAgent())
     webview()->devToolsAgent()->setLayerTreeId(rwc->GetLayerTreeId());
 
-#if !defined(OS_MACOSX)  // many events are unhandled - http://crbug.com/138003
-  RenderThreadImpl* render_thread = RenderThreadImpl::current();
-  // render_thread may be NULL in tests.
-  InputHandlerManager* input_handler_manager =
-      render_thread ? render_thread->input_handler_manager() : NULL;
-  if (input_handler_manager) {
-    input_handler_manager->AddInputHandler(
-        routing_id_, rwc->GetInputHandler(), AsWeakPtr());
-  }
+  bool use_threaded_event_handling = true;
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+  // Development flag because many events are still unhandled on Mac.
+  // http://crbug.com/138003
+  use_threaded_event_handling = CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableThreadedEventHandlingMac);
 #endif
+  if (use_threaded_event_handling) {
+    RenderThreadImpl* render_thread = RenderThreadImpl::current();
+    // render_thread may be NULL in tests.
+    InputHandlerManager* input_handler_manager =
+        render_thread ? render_thread->input_handler_manager() : NULL;
+    if (input_handler_manager) {
+      input_handler_manager->AddInputHandler(
+          routing_id_, rwc->GetInputHandler(), AsWeakPtr());
+    }
+  }
 }
 
 // blink::WebFrameClient -----------------------------------------------------
-- 
2.11.4.GIT