Add fixed raster scale use counter histograms.

cc/trees/layer_tree_host_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_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <stddef.h>
 
+#include <bitset>
 #include <memory>
 #include <set>
 #include <string>
 #include <unordered_map>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "cc/animation/layer_tree_mutator.h"
@@ skipping 587 matching lines @@
                                        ScrollNode* scroll_node) const;
 
   // Returns true if a scroll offset animation is created and false if we scroll
   // by the desired amount without an animation.
   bool ScrollAnimationCreate(ScrollNode* scroll_node,
                              const gfx::Vector2dF& scroll_amount);
 
   void SetLayerTreeMutator(LayerTreeMutator* mutator);
   LayerTreeMutator* mutator() { return mutator_; }
 
+  void set_fixed_raster_scale_has_blurry_content() {
+    has_fixed_raster_scale_blurry_content_ = true;
+  }
+  bool has_fixed_raster_scale_blurry_content() const {
+    return has_fixed_raster_scale_blurry_content_;
+  }
+
+  bool HasFixedRasterScalePotentialPerformanceRegression() const;
+  void SetFixedRasterScaleAttemptedToChangeScale();
+
  protected:
   LayerTreeHostImpl(
       const LayerTreeSettings& settings,
       LayerTreeHostImplClient* client,
       TaskRunnerProvider* task_runner_provider,
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
       TaskGraphRunner* task_graph_runner,
       int id);
 
   // Virtual for testing.
   virtual bool AnimateLayers(base::TimeTicks monotonic_time);
 
   bool is_likely_to_require_a_draw() const {
     return is_likely_to_require_a_draw_;
   }
 
   // Removes empty or orphan RenderPasses from the frame.
   static void RemoveRenderPasses(FrameData* frame);
 
   LayerTreeHostImplClient* client_;
   TaskRunnerProvider* task_runner_provider_;
 
   BeginFrameTracker current_begin_frame_tracker_;
 
  private:
+  enum {
+    kFixedRasterScaleAttemptedScaleChangeThreshold = 5,

[danakj, 2016/05/05 00:09:49]

1 value per if you're doing this with enums.

enum {a=1}
enum {b=2}

[vmpstr, 2016/05/05 01:33:51]

Done.

+    kFixedRasterScaleAttemptedScaleChangeHistoryCount = 10
+  };
+
   gfx::Vector2dF ScrollNodeWithViewportSpaceDelta(
       ScrollNode* scroll_node,
       const gfx::PointF& viewport_point,
       const gfx::Vector2dF& viewport_delta,
       ScrollTree* scroll_tree);
 
   void CreateAndSetRenderer();
   void CleanUpTileManagerAndUIResources();
   void CreateTileManagerResources();
   void ReleaseTreeResources();
@@ skipping 183 matching lines @@
 
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   bool requires_high_res_to_draw_;
   bool is_likely_to_require_a_draw_;
 
   std::unique_ptr<Viewport> viewport_;
 
   LayerTreeMutator* mutator_;
 
+  bool has_fixed_raster_scale_blurry_content_;
+  std::bitset<kFixedRasterScaleAttemptedScaleChangeHistoryCount>
+      fixed_raster_scale_attempted_scale_change_history_;
+
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_