Add chromium side flag for enabling/disabling layer squashing.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 6d36600d3e0c3386d2db5c0ede53bcdfa66bd27e..ddd769f694c687c4d9221241335de44df1692860 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -91,6 +91,10 @@ const char kDisableAcceleratedLayers[]      = "disable-accelerated-layers";
 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";
@@ -346,6 +350,11 @@ const char kEnableAcceleratedFixedRootBackground[] =
 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[] =