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

cc/switches.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/switches.h"
 
 namespace cc {
 namespace switches {
 
 // On platforms where checkerboards are used, prefer background colors instead
 // of checkerboards.
 const char kBackgroundColorInsteadOfCheckerboard[] =
     "background-color-instead-of-checkerboard";
 
 const char kDisableThreadedAnimation[]      = "disable-threaded-animation";
 
 // Send a message for every frame from the impl thread to the parent compositor.
 const char kEnableCompositorFrameMessage[] = "enable-compositor-frame-message";
 
 // Paint content on the compositor thread instead of the main thread.
 const char kEnableImplSidePainting[] = "enable-impl-side-painting";
 
 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 density compensated pixels.
+const char kTopControlsHeight[] = "top-controls-height";
+
 // Number of worker threads used to rasterize content.
 const char kNumRasterThreads[] = "num-raster-threads";
 
 // Show rects in the HUD around layers whose properties have changed.
 const char kShowPropertyChangedRects[] = "show-property-changed-rects";
 
 // Show rects in the HUD around damage as it is recorded into each render
 // surface.
 const char kShowSurfaceDamageRects[] = "show-surface-damage-rects";
 
@@ skipping 12 matching lines @@
 // Show rects in the HUD wherever something is not known to be drawn opaque and
 // is not considered to be occluding the pixels behind it.
 const char kShowNonOccludingRects[] = "show-nonoccluding-rects";
 
 // Show metrics about overdraw in about:tracing recordings, such as the number
 // of pixels culled, and the number of pixels drawn, for each frame.
 const char kTraceOverdraw[] = "trace-overdraw";
 
 }  // namespace switches
 }  // namespace cc