cc: Fix recording of GPU rasterization histogram for renderer compositor.

cc/trees/layer_tree_host.cc

 // Copyright 2011 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/trees/layer_tree_host.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 719 matching lines @@
     Layer* found = FindFirstScrollableLayer(layer->children()[i].get());
     if (found)
       return found;
   }
 
   return NULL;
 }
 
 void LayerTreeHost::RecordGpuRasterizationHistogram() {
   // Gpu rasterization is only supported for Renderer compositors.
-  // Checking for IsThreaded() to exclude Browser compositors.
-  if (gpu_rasterization_histogram_recorded_ || IsThreaded())
+  // Checking for IsSingleThreaded() to exclude Browser compositors.
+  if (gpu_rasterization_histogram_recorded_ || IsSingleThreaded())

[vmpstr, 2015/12/10 00:35:00]

It would be nice to add a test so this doesn't regress. Is it possible to write
a test that checks that gpu_rasterization_histogram_recorded_ doesn't become
true if this is run in single threaded mode?

     return;
 
   // Record how widely gpu rasterization is enabled.
   // This number takes device/gpu whitelisting/backlisting into account.
   // Note that we do not consider the forced gpu rasterization mode, which is
   // mostly used for debugging purposes.
   UMA_HISTOGRAM_BOOLEAN("Renderer4.GpuRasterizationEnabled",
                         settings_.gpu_rasterization_enabled);
   if (settings_.gpu_rasterization_enabled) {
     UMA_HISTOGRAM_BOOLEAN("Renderer4.GpuRasterizationTriggered",
@@ skipping 505 matching lines @@
   return compositor_mode_ == CompositorMode::SingleThreaded;
 }
 
 bool LayerTreeHost::IsThreaded() const {
   DCHECK(compositor_mode_ != CompositorMode::Threaded ||
          task_runner_provider_->HasImplThread());
   return compositor_mode_ == CompositorMode::Threaded;
 }
 
 }  // namespace cc