cc: Simplify the logic for deciding to update tile priorities.

cc/layers/layer_impl.h

 // 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.
 
 #ifndef CC_LAYERS_LAYER_IMPL_H_
 #define CC_LAYERS_LAYER_IMPL_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 92 matching lines @@
                            AppendQuadsData* append_quads_data) {}
   virtual void DidDraw(ResourceProvider* resource_provider);
 
   virtual ResourceProvider::ResourceId ContentsResourceId() const;
 
   virtual bool HasDelegatedContent() const;
   virtual bool HasContributingDelegatedRenderPasses() const;
   virtual RenderPass::Id FirstContributingRenderPassId() const;
   virtual RenderPass::Id NextContributingRenderPassId(RenderPass::Id id) const;
 
+  virtual bool NeedsFirstTimeUpdateTilePriorities() const;
   virtual void UpdateTilePriorities() {}
 
   virtual ScrollbarLayerImpl* ToScrollbarLayer();
 
   // Returns true if this layer has content to draw.
   void SetDrawsContent(bool draws_content);
   bool DrawsContent() const { return draws_content_; }
 
   bool force_render_surface() const { return force_render_surface_; }
   void SetForceRenderSurface(bool force) { force_render_surface_ = force; }
@@ skipping 409 matching lines @@
   // Group of properties that need to be computed based on the layer tree
   // hierarchy before layers can be drawn.
   DrawProperties<LayerImpl, RenderSurfaceImpl> draw_properties_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_H_