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

cc/switches.h

Index: cc/switches.h
diff --git a/cc/switches.h b/cc/switches.h
index e3797bb9fab4bd59f80dbccd5670918f7138057d..e36b01df8712709a0a4031a203703f8e97b83b0e 100644
--- a/cc/switches.h
+++ b/cc/switches.h
@@ -21,6 +21,7 @@ CC_EXPORT extern const char kEnableCompositorFrameMessage[];
 CC_EXPORT extern const char kEnableImplSidePainting[];
 CC_EXPORT extern const char kEnablePartialSwap[];
 CC_EXPORT extern const char kEnablePerTilePainting[];
+CC_EXPORT extern const char kEnableTopControlsPositionCalculation[];
 CC_EXPORT extern const char kJankInsteadOfCheckerboard[];
 CC_EXPORT extern const char kNumRasterThreads[];
 CC_EXPORT extern const char kShowPropertyChangedRects[];
@@ -30,6 +31,7 @@ CC_EXPORT extern const char kShowReplicaScreenSpaceRects[];
 CC_EXPORT extern const char kShowOccludingRects[];
 CC_EXPORT extern const char kShowNonOccludingRects[];
 CC_EXPORT extern const char kTraceOverdraw[];
+CC_EXPORT extern const char kTopControlsHeight[];
 
 }  // namespace switches
 }  // namespace cc