Add some traces for when render pass caching fails

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 "cc/layer_tree_host_impl.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/debug/trace_event.h"
@@ skipping 683 matching lines @@
         if (currentQuad->material != DrawQuad::RENDER_PASS)
             continue;
 
         RenderPass::Id nextRemoveRenderPassId = RenderPassDrawQuad::MaterialCast(currentQuad)->render_pass_id;
         removeRenderPassesRecursive(nextRemoveRenderPassId, frame);
     }
 }
 
 bool LayerTreeHostImpl::CullRenderPassesWithCachedTextures::shouldRemoveRenderPass(const RenderPassDrawQuad& quad, const FrameData&) const
 {
-    return quad.contents_changed_since_last_frame.IsEmpty() && m_renderer.haveCachedResourcesForRenderPassId(quad.render_pass_id);
+    if (!quad.contents_changed_since_last_frame.IsEmpty()) {
+        TRACE_EVENT0("cc", "CullRenderPassesWithCachedTextures have damage");
+        return false;
+    } else if (!m_renderer.haveCachedResourcesForRenderPassId(quad.render_pass_id)) {
+        TRACE_EVENT0("cc", "CullRenderPassesWithCachedTextures have no texture");
+        return false;
+    }
+    TRACE_EVENT0("cc", "CullRenderPassesWithCachedTextures dropped!");
+    return true;
 }
 
 bool LayerTreeHostImpl::CullRenderPassesWithNoQuads::shouldRemoveRenderPass(const RenderPassDrawQuad& quad, const FrameData& frame) const
 {
     const RenderPass* renderPass = findRenderPassById(quad.render_pass_id, frame);
     const RenderPassList& renderPasses = frame.renderPasses;
     RenderPassList::const_iterator foundPass = std::find(renderPasses.begin(), renderPasses.end(), renderPass);
 
     bool renderPassAlreadyRemoved = foundPass == renderPasses.end();
     if (renderPassAlreadyRemoved)
@@ skipping 1008 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