Add UMA stats for SurfaceDrawQuads in SurfaceAggregator.

cc/surfaces/surface_aggregator.h

 // Copyright 2014 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_SURFACES_SURFACE_AGGREGATOR_H_
 #define CC_SURFACES_SURFACE_AGGREGATOR_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 58 matching lines @@
     bool may_contain_video = false;
   };
 
   struct RenderPassInfo {
     // This is the id the pass is mapped to.
     int id;
     // This is true if the pass was used in the last aggregated frame.
     bool in_use = true;
   };
 
+  struct SurfaceDrawQuadUmaStats {
+    void Reset() {
+      valid_surface = 0;
+      missing_surface = 0;
+      no_active_frame = 0;
+    }
+
+    // The surface exists and has an active frame.
+    int valid_surface;
+    // The surface doesn't exist.
+    int missing_surface;
+    // The surface exists but doesn't have an active frame.
+    int no_active_frame;
+  };
+
   ClipData CalculateClipRect(const ClipData& surface_clip,
                              const ClipData& quad_clip,
                              const gfx::Transform& target_transform);
 
   int RemapPassId(int surface_local_pass_id, const SurfaceId& surface_id);
 
   void HandleSurfaceQuad(const SurfaceDrawQuad* surface_quad,
                          const gfx::Transform& target_transform,
                          const ClipData& clip_rect,
                          RenderPass* dest_pass,
@@ skipping 97 matching lines @@
   // The root damage rect of the currently-aggregating frame.
   gfx::Rect root_damage_rect_;
 
   // True if the frame that's currently being aggregated has copy requests.
   // This is valid during Aggregate after PrewalkTree is called.
   bool has_copy_requests_;
 
   // Resource list for the aggregated frame.
   TransferableResourceArray* dest_resource_list_;
 
+  // Tracks UMA stats for SurfaceDrawQuads during a call to Aggregate().
+  SurfaceDrawQuadUmaStats uma_stats_;
+
   base::WeakPtrFactory<SurfaceAggregator> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceAggregator);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_AGGREGATOR_H_