Add chromium side flag for enabling/disabling layer squashing.

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 {
 
 // The number of MSAA samples for canvas2D. Requires MSAA support by GPU to
 // have an effect. 0 disables MSAA.
@@ skipping 73 matching lines @@
 const char kDisableAcceleratedFixedRootBackground[] =
     "disable-accelerated-fixed-root-background";
 
 // Disables the hardware acceleration of 3D CSS and animation.
 const char kDisableAcceleratedLayers[]      = "disable-accelerated-layers";
 
 // Disables accelerated compositing for overflow scroll.
 const char kDisableAcceleratedOverflowScroll[] =
     "disable-accelerated-overflow-scroll";
 
+// Disables layer squashing.
+const char kDisableLayerSquashing[] =
+    "disable-layer-squashing";
+
 // Disable accelerated compositing for scrollable frames.
 const char kDisableAcceleratedScrollableFrames[] =
      "disable-accelerated-scrollable-frames";
 
 // Disables the hardware acceleration of plugins.
 const char kDisableAcceleratedPlugins[]     = "disable-accelerated-plugins";
 
 // Disables GPU accelerated video display.
 const char kDisableAcceleratedVideo[]       = "disable-accelerated-video";
 
@@ skipping 235 matching lines @@
 // Enables accelerated compositing for backgrounds of root layers with
 // background-attachment: fixed. Requires kForceCompositingMode.
 const char kEnableAcceleratedFixedRootBackground[] =
     "enable-accelerated-fixed-root-background";
 
 // Enables accelerated compositing for overflow scroll. Promotes eligible
 // overflow:scroll elements to layers to enable accelerated scrolling for them.
 const char kEnableAcceleratedOverflowScroll[] =
     "enable-accelerated-overflow-scroll";
 
+// Enables experimental feature that maps multiple RenderLayers to
+// one composited layer to avoid pathological layer counts.
+const char kEnableLayerSquashing[] =
+    "enable-layer-squashing";
+
 // Enables accelerated compositing for scrollable frames for accelerated
 // scrolling for them. Requires kForceCompositingMode.
 const char kEnableAcceleratedScrollableFrames[] =
      "enable-accelerated-scrollable-frames";
 
 // Turns on extremely verbose logging of accessibility events.
 const char kEnableAccessibilityLogging[]    = "enable-accessibility-logging";
 
 // Use a BeginImplFrame signal from browser to renderer to schedule rendering.
 const char kEnableBeginFrameScheduling[]    = "enable-begin-frame-scheduling";
@@ skipping 649 matching lines @@
 #endif
 
 #if defined(OS_POSIX)
 // Causes the child processes to cleanly exit via calling exit().
 const char kChildCleanExit[]                = "child-clean-exit";
 #endif
 
 // Don't dump stuff here, follow the same order as the header.
 
 }  // namespace switches