cc: Turn overdraw metrics on only when about:tracing is recording.

cc/layer_tree_host_impl.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 "config.h"
 
 #include "cc/layer_tree_host_impl.h"
 
 #include "base/basictypes.h"
 #include "base/debug/trace_event.h"
@@ skipping 363 matching lines @@
     calculateRenderSurfaceLayerList(*frame.renderSurfaceLayerList);
 
     TRACE_EVENT1("cc", "LayerTreeHostImpl::calculateRenderPasses", "renderSurfaceLayerList.size()", static_cast<long long unsigned>(frame.renderSurfaceLayerList->size()));
 
     // Create the render passes in dependency order.
     for (int surfaceIndex = frame.renderSurfaceLayerList->size() - 1; surfaceIndex >= 0 ; --surfaceIndex) {
         LayerImpl* renderSurfaceLayer = (*frame.renderSurfaceLayerList)[surfaceIndex];
         renderSurfaceLayer->renderSurface()->appendRenderPasses(frame);
     }
 
-    bool recordMetricsForFrame = true; // FIXME: In the future, disable this when about:tracing is off.
+    bool recordMetricsForFrame = base::debug::TraceLog::GetInstance() && base::debug::TraceLog::GetInstance()->IsEnabled();
     OcclusionTrackerImpl occlusionTracker(m_rootLayerImpl->renderSurface()->contentRect(), recordMetricsForFrame);
     occlusionTracker.setMinimumTrackingSize(m_settings.minimumOcclusionTrackingSize);
 
     if (settings().showOccludingRects)
         occlusionTracker.setOccludingScreenSpaceRectsContainer(&frame.occludingScreenSpaceRects);
 
     // Add quads to the Render passes in FrontToBack order to allow for testing occlusion and performing culling during the tree walk.
     typedef LayerIterator<LayerImpl, std::vector<LayerImpl*>, RenderSurfaceImpl, LayerIteratorActions::FrontToBack> LayerIteratorType;
 
     // Typically when we are missing a texture and use a checkerboard quad, we still draw the frame. However when the layer being
@@ skipping 1078 matching lines @@
     ScrollbarAnimationController* scrollbarController = layer->scrollbarAnimationController();
     double monotonicTime = (time - base::TimeTicks()).InSecondsF();
     if (scrollbarController && scrollbarController->animate(monotonicTime))
         m_client->setNeedsRedrawOnImplThread();
 
     for (size_t i = 0; i < layer->children().size(); ++i)
         animateScrollbarsRecursive(layer->children()[i], time);
 }
 
 }  // namespace cc