Revert of Delete the enable/disable layer squashing flags and settings.

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 569585826c9815f2a2db94ecec3afb711b2d68cd..3b3a8270811fbb128d991371f1567552069549c5 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -81,6 +81,10 @@
 // Disable gpu-accelerated 2d canvas.
 const char kDisableAccelerated2dCanvas[]    = "disable-accelerated-2d-canvas";
 
+// Disables layer squashing.
+const char kDisableLayerSquashing[] =
+    "disable-layer-squashing";
+
 // Disables hardware acceleration of video decode, where available.
 const char kDisableAcceleratedVideoDecode[] =
     "disable-accelerated-video-decode";
@@ -301,6 +305,11 @@
 // Enables using signed distance fields when rendering text.
 // Only valid if GPU rasterization is enabled as well.
 const char kEnableDistanceFieldText[]       = "enable-distance-field-text";
+
+// Enables experimental feature that maps multiple RenderLayers to
+// one composited layer to avoid pathological layer counts.
+const char kEnableLayerSquashing[] =
+    "enable-layer-squashing";
 
 // Enable the experimental Credential Manager JavaScript API.
 const char kEnableCredentialManagerAPI[]    = "enable-credential-manager-api";