Add runtime flag to enable the display list 2D canvas implementation

content/child/runtime_features.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/runtime_features.h"
 
 #include "base/command_line.h"
 #include "content/common/content_switches_internal.h"
 #include "content/public/common/content_switches.h"
 #include "third_party/WebKit/public/web/WebRuntimeFeatures.h"
@@ skipping 108 matching lines @@
 
   if (command_line.HasSwitch(switches::kDisableFileSystem))
     WebRuntimeFeatures::enableFileSystem(false);
 
   if (command_line.HasSwitch(switches::kEnableExperimentalCanvasFeatures))
     WebRuntimeFeatures::enableExperimentalCanvasFeatures(true);
 
   if (command_line.HasSwitch(switches::kEnableSpeechSynthesis))
     WebRuntimeFeatures::enableSpeechSynthesis(true);
 
+  if (command_line.HasSwitch(switches::kEnableDisplayList2dCanvas))

[piman, 2014/07/21 21:45:56]

This will require you to forward the switch to the renderer (see
RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer).

What is the relationship between the WebRuntimeFeatures flag and the
WebPreferences flag? e.g. if one is set but not the other one? If they need to
match, can we add a check?

[Justin Novosad, 2014/07/23 18:56:18]

Done.

+    WebRuntimeFeatures::enableDisplayList2dCanvas(true);
+
   if (command_line.HasSwitch(switches::kEnableWebGLDraftExtensions))
     WebRuntimeFeatures::enableWebGLDraftExtensions(true);
 
   if (command_line.HasSwitch(switches::kEnableWebGLImageChromium))
     WebRuntimeFeatures::enableWebGLImageChromium(true);
 
   if (command_line.HasSwitch(switches::kEnableOverlayFullscreenVideo))
     WebRuntimeFeatures::enableOverlayFullscreenVideo(true);
 
   if (ui::IsOverlayScrollbarEnabled())
@@ skipping 12 matching lines @@
     WebRuntimeFeatures::enableBleedingEdgeFastPaths(true);
 
   if (command_line.HasSwitch(switches::kEnablePreciseMemoryInfo))
     WebRuntimeFeatures::enablePreciseMemoryInfo(true);
 
   if (command_line.HasSwitch(switches::kEnableLayerSquashing))
     WebRuntimeFeatures::enableLayerSquashing(true);
 }
 
 }  // namespace content