Update from https://crrev.com/303153

cc/base/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/base/switches.h"
 
 #include "base/command_line.h"
 
 namespace cc {
 namespace switches {
@@ skipping 54 matching lines @@
 const char kUIDisablePartialSwap[] = "ui-disable-partial-swap";
 
 // Enables the GPU benchmarking extension
 const char kEnableGpuBenchmarking[] = "enable-gpu-benchmarking";
 
 // Renders a border around compositor layers to help debug and study
 // layer compositing.
 const char kShowCompositedLayerBorders[] = "show-composited-layer-borders";
 const char kUIShowCompositedLayerBorders[] = "ui-show-layer-borders";
 
-// Draws a FPS indicator
+// Draws a heads-up-display showing Frames Per Second as well as GPU memory
+// usage. If you also use --vmodule="head*=1" then FPS will also be output to
+// the console log.
 const char kShowFPSCounter[] = "show-fps-counter";
 const char kUIShowFPSCounter[] = "ui-show-fps-counter";
 
 // Renders a border that represents the bounding box for the layer's animation.
 const char kShowLayerAnimationBounds[] = "show-layer-animation-bounds";
 const char kUIShowLayerAnimationBounds[] = "ui-show-layer-animation-bounds";
 
 // Show rects in the HUD around layers whose properties have changed.
 const char kShowPropertyChangedRects[] = "show-property-changed-rects";
 const char kUIShowPropertyChangedRects[] = "ui-show-property-changed-rects";
@@ skipping 25 matching lines @@
 const char kUIShowNonOccludingRects[] = "ui-show-nonoccluding-rects";
 
 // Prevents the layer tree unit tests from timing out.
 const char kCCLayerTreeTestNoTimeout[] = "cc-layer-tree-test-no-timeout";
 
 // Makes pixel tests write their output instead of read it.
 const char kCCRebaselinePixeltests[] = "cc-rebaseline-pixeltests";
 
 }  // namespace switches
 }  // namespace cc