Add a switch to enable compositing for scrollable frames.

webkit/glue/webpreferences.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 "webkit/glue/webpreferences.h"
 
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebNetworkStateNotifier.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebRuntimeFeatures.h"
@@ skipping 64 matching lines @@
       experimental_webgl_enabled(false),
       flash_3d_enabled(true),
       flash_stage3d_enabled(false),
       gl_multisampling_enabled(true),
       privileged_webgl_extensions_enabled(false),
       webgl_errors_to_console_enabled(true),
       show_composited_layer_borders(false),
       show_composited_layer_tree(false),
       show_fps_counter(false),
       accelerated_compositing_for_overflow_scroll_enabled(false),
+      accelerated_compositing_for_scrollable_frames_enabled(false),
       show_paint_rects(false),
       render_vsync_enabled(true),
       asynchronous_spell_checking_enabled(true),
       unified_textchecker_enabled(false),
       accelerated_compositing_enabled(false),
       force_compositing_mode(false),
       fixed_position_compositing_enabled(false),
       accelerated_compositing_for_3d_transforms_enabled(false),
       accelerated_compositing_for_animation_enabled(false),
       accelerated_compositing_for_video_enabled(false),
@@ skipping 242 matching lines @@
   // on command line.
   settings->setShowDebugBorders(show_composited_layer_borders);
 
   // Display an FPS indicator if requested on the command line.
   settings->setShowFPSCounter(show_fps_counter);
 
   // Enables accelerated compositing for overflow scroll.
   settings->setAcceleratedCompositingForOverflowScrollEnabled(
       accelerated_compositing_for_overflow_scroll_enabled);
 
+  // Enables accelerated compositing for scrollable frames if requested on
+  // command line.
+  settings->setAcceleratedCompositingForScrollableFramesEnabled(
+      accelerated_compositing_for_scrollable_frames_enabled);
+
   // Display the current compositor tree as overlay if requested on
   // the command line
   settings->setShowPlatformLayerTree(show_composited_layer_tree);
 
   // Display visualization of what has changed on the screen using an
   // overlay of rects, if requested on the command line.
   settings->setShowPaintRects(show_paint_rects);
 
   // Set whether to throttle framerate to Vsync.
   settings->setRenderVSyncEnabled(render_vsync_enabled);
@@ skipping 93 matching lines @@
   settings->setDoubleTapToZoomEnabled(true);
   settings->setMediaPlaybackRequiresUserGesture(
       user_gesture_required_for_media_playback);
   settings->setSupportsMultipleWindows(supports_multiple_windows);
 #endif
 
   WebNetworkStateNotifier::setOnLine(is_online);
 }
 
 }  // namespace webkit_glue