Add the "experimental canvas features" flag, and plumb it through to

content/public/common/content_switches.cc

 // Copyright (c) 2012 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/public/common/content_switches.h"
 
 namespace switches {
 
 // By default, file:// URIs cannot read other file:// URIs. This is an
 // override for developers who need the old behavior for testing.
@@ skipping 26 matching lines @@
 // enable/disable switches to avoid accidentally regressing the policy
 // support for controlling access to these APIs.
 const char kDisable3DAPIs[]                 = "disable-3d-apis";
 
 // Disable gpu-accelerated 2d canvas.
 const char kDisableAccelerated2dCanvas[]    = "disable-accelerated-2d-canvas";
 
 // Disable antialiasing on 2d canvas.
 const char kDisable2dCanvasAntialiasing[]   = "disable-canvas-aa";
 
+// Enable experimental canvas features, e.g. canvas 2D context attributes
+const char kEnableExperimentalCanvasFeatures[]
+                                        = "enable-experimental-canvas-features";
+
 // Disables accelerated compositing.
 const char kDisableAcceleratedCompositing[] = "disable-accelerated-compositing";
 
 // Disables the hardware acceleration of 3D CSS and animation.
 const char kDisableAcceleratedLayers[]      = "disable-accelerated-layers";
 
 // Disables the hardware acceleration of plugins.
 const char kDisableAcceleratedPlugins[]     = "disable-accelerated-plugins";
 
 // Disables GPU accelerated video display.
@@ skipping 728 matching lines @@
 // Enables or disables history navigation in response to horizontal overscroll.
 // Set the value to '1' to enable the feature, and set to '0' to disable.
 // Defaults to enabled.
 const char kOverscrollHistoryNavigation[] =
     "overscroll-history-navigation";
 
 // Enables 'image/webp' accept header for image requests.
 const char kEnableWebPInAcceptHeader[] = "enable-webp-in-accept-header";
 
 }  // namespace switches