cc: Avoid expensive RenderingStats collection.

cc/bitmap_content_layer_updater.cc

Index: cc/bitmap_content_layer_updater.cc
diff --git a/cc/bitmap_content_layer_updater.cc b/cc/bitmap_content_layer_updater.cc
index 222ab21146240e43b0c9610aa88c2d7da21f695f..2dd4d2934e36170f54decaa22494a83af3437712 100644
--- a/cc/bitmap_content_layer_updater.cc
+++ b/cc/bitmap_content_layer_updater.cc
@@ -23,7 +23,7 @@ BitmapContentLayerUpdater::Resource::~Resource()
 {
 }
 
-void BitmapContentLayerUpdater::Resource::update(ResourceUpdateQueue& queue, const gfx::Rect& sourceRect, const gfx::Vector2d& destOffset, bool partialUpdate, RenderingStats&)
+void BitmapContentLayerUpdater::Resource::update(ResourceUpdateQueue& queue, const gfx::Rect& sourceRect, const gfx::Vector2d& destOffset, bool partialUpdate, RenderingStats*)
 {
     updater()->updateTexture(queue, texture(), sourceRect, destOffset, partialUpdate);
 }
@@ -48,14 +48,15 @@ scoped_ptr<LayerUpdater::Resource> BitmapContentLayerUpdater::createResource(Pri
     return scoped_ptr<LayerUpdater::Resource>(new Resource(this, PrioritizedResource::create(manager)));
 }
 
-void BitmapContentLayerUpdater::prepareToUpdate(const gfx::Rect& contentRect, const gfx::Size& tileSize, float contentsWidthScale, float contentsHeightScale, gfx::Rect& resultingOpaqueRect, RenderingStats& stats)
+void BitmapContentLayerUpdater::prepareToUpdate(const gfx::Rect& contentRect, const gfx::Size& tileSize, float contentsWidthScale, float contentsHeightScale, gfx::Rect& resultingOpaqueRect, RenderingStats* stats)
 {
     if (m_canvasSize != contentRect.size()) {
         m_canvasSize = contentRect.size();
         m_canvas = make_scoped_ptr(skia::CreateBitmapCanvas(m_canvasSize.width(), m_canvasSize.height(), m_opaque));
     }
 
-    stats.totalPixelsRasterized += contentRect.width() * contentRect.height();
+    if (stats)
+      stats->totalPixelsRasterized += contentRect.width() * contentRect.height();
 
     paintContents(m_canvas.get(), contentRect, contentsWidthScale, contentsHeightScale, resultingOpaqueRect, stats);
 }