cc: Avoid expensive RenderingStats collection.

cc/scrollbar_layer.cc

 // Copyright 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/scrollbar_layer.h"
 
 #include "base/basictypes.h"
 #include "base/debug/trace_event.h"
 #include "cc/caching_bitmap_content_layer_updater.h"
 #include "cc/layer_painter.h"
@@ skipping 230 matching lines @@
         if (!m_foreTrack)
             m_foreTrack = m_foreTrackUpdater->createResource(layerTreeHost()->contentsTextureManager());
     }
 
     if (!m_thumbUpdater)
         m_thumbUpdater = CachingBitmapContentLayerUpdater::Create(ScrollbarThumbPainter::create(m_scrollbar.get(), m_painter.get(), m_geometry.get()).PassAs<LayerPainter>());
     if (!m_thumb)
         m_thumb = m_thumbUpdater->createResource(layerTreeHost()->contentsTextureManager());
 }
 
-void ScrollbarLayer::updatePart(CachingBitmapContentLayerUpdater* painter, LayerUpdater::Resource* resource, const gfx::Rect& rect, ResourceUpdateQueue& queue, RenderingStats& stats)
+void ScrollbarLayer::updatePart(CachingBitmapContentLayerUpdater* painter, LayerUpdater::Resource* resource, const gfx::Rect& rect, ResourceUpdateQueue& queue, RenderingStats* stats)
 {
     // Skip painting and uploading if there are no invalidations and
     // we already have valid texture data.
     if (resource->texture()->haveBackingTexture() &&
         resource->texture()->size() == rect.size() &&
         !isDirty())
         return;
 
     // We should always have enough memory for UI.
     DCHECK(resource->texture()->canAcquireBackingTexture());
@@ skipping 42 matching lines @@
         m_foreTrack->texture()->setDimensions(contentBounds(), m_textureFormat);
         m_foreTrack->texture()->setRequestPriority(PriorityCalculator::uiPriority(drawsToRoot));
     }
     if (m_thumb) {
         gfx::Size thumbSize = scrollbarLayerRectToContentRect(m_geometry->thumbRect(m_scrollbar.get())).size();
         m_thumb->texture()->setDimensions(thumbSize, m_textureFormat);
         m_thumb->texture()->setRequestPriority(PriorityCalculator::uiPriority(drawsToRoot));
     }
 }
 
-void ScrollbarLayer::update(ResourceUpdateQueue& queue, const OcclusionTracker* occlusion, RenderingStats& stats)
+void ScrollbarLayer::update(ResourceUpdateQueue& queue, const OcclusionTracker* occlusion, RenderingStats* stats)
 {
     ContentsScalingLayer::update(queue, occlusion, stats);
 
     m_dirtyRect.Union(m_updateRect);
     if (contentBounds().IsEmpty())
         return;
     if (visibleContentRect().IsEmpty())
         return;
 
     createUpdaterIfNeeded();
 
     gfx::Rect contentRect = scrollbarLayerRectToContentRect(gfx::Rect(m_scrollbar->location(), bounds()));
     updatePart(m_backTrackUpdater.get(), m_backTrack.get(), contentRect, queue, stats);
     if (m_foreTrack && m_foreTrackUpdater)
         updatePart(m_foreTrackUpdater.get(), m_foreTrack.get(), contentRect, queue, stats);
 
     // Consider the thumb to be at the origin when painting.
     gfx::Rect thumbRect = m_geometry->thumbRect(m_scrollbar.get());
     m_thumbSize = thumbRect.size();
     gfx::Rect originThumbRect = scrollbarLayerRectToContentRect(gfx::Rect(thumbRect.size()));
     if (!originThumbRect.IsEmpty())
         updatePart(m_thumbUpdater.get(), m_thumb.get(), originThumbRect, queue, stats);
 
     m_dirtyRect = gfx::RectF();
 }
 
 }  // namespace cc