Record size of scroller that user scrolls

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>
@@ skipping 587 matching lines @@
 
   void SetLayerTreeMutator(std::unique_ptr<LayerTreeMutator> mutator);
   LayerTreeMutator* mutator() { return mutator_.get(); }
 
   LayerImpl* ViewportMainScrollLayer();
 
   void QueueImageDecode(sk_sp<const SkImage> image,
                         const base::Callback<void(bool)>& embedder_callback);
   std::vector<base::Closure> TakeCompletedImageDecodeCallbacks();
 
+  static const int maxScrollerSize = 200000;  // 400px * 500px
+  static const int bucketNum = 50;

[tdresser, 2017/03/30 15:19:06]

Prefix with "k"

https://google.github.io/styleguide/cppguide.html#Constant_Names

[weiliangc, 2017/03/30 19:19:36]

These two are just constants. Is it possible to put it in a header file
somewhere that can be included by both layer_tree_host_impl.cc and blink/core?
It doesn't seem like the constants need to be living on LayerTreeHostImpl class.

+
  protected:
   LayerTreeHostImpl(
       const LayerTreeSettings& settings,
       LayerTreeHostImplClient* client,
       TaskRunnerProvider* task_runner_provider,
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       TaskGraphRunner* task_graph_runner,
       std::unique_ptr<MutatorHost> mutator_host,
       int id,
       scoped_refptr<base::SequencedTaskRunner> image_worker_task_runner);
@@ skipping 234 matching lines @@
   // These callbacks are stored here to be transfered to the main thread when we
   // begin main frame. These callbacks must only be called on the main thread.
   std::vector<base::Closure> completed_image_decode_callbacks_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_