ui: Add debug flag to show composited layer borders in ChromeOS UI.

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index fca84ca3284ee431e2d5019e05a5fc3f001e6e46..ba99eb035f868049d30ebd44093b904b94a00c0b 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -59,6 +59,9 @@ const char kEnableSurfaceSynchronization[] = "enable-surface-synchronization";
 // layer compositing.
 const char kShowCompositedLayerBorders[] = "show-composited-layer-borders";
 const char kUIShowCompositedLayerBorders[] = "ui-show-layer-borders";
+const char kCompositedRenderpassBorders[] = "renderpass";
+const char kCompositedSurfaceBorders[] = "surface";
+const char kCompositedLayerBorders[] = "layer";
 
 // Renders a green border around GL composited texture quads to help
 // debug and study overlay support.