Add support for calculating the position of the top controls in the cc layer.

cc/switches.cc

Index: cc/switches.cc
diff --git a/cc/switches.cc b/cc/switches.cc
index 2cbb459a7ed85ce984827065dd2aab8471676a10..cba392de210d53dfe59a4d6e25d6d4e15fe6f0dd 100644
--- a/cc/switches.cc
+++ b/cc/switches.cc
@@ -24,6 +24,12 @@ const char kEnablePartialSwap[]             = "enable-partial-swap";
 
 const char kEnablePerTilePainting[]         = "enable-per-tile-painting";
 
+const char kEnableTopControlsPositionCalculation[] =
+    "enable-top-controls-position-calculation";
+
+// The height of the movable top controls in screen pixels.
+const char kTopControlsHeight[] = "top-controls-height";
+
 // Number of worker threads used to rasterize content.
 const char kNumRasterThreads[] = "num-raster-threads";