cc: Add TileManager interface that allows LTHI to determine when to activate pending tree.

cc/tile_manager.h

Index: cc/tile_manager.h
diff --git a/cc/tile_manager.h b/cc/tile_manager.h
index d80e2f1a0b1860441c47e99a947c139821a788a8..b479e9496cc930fb43626023267a09db3ea6dc47 100644
--- a/cc/tile_manager.h
+++ b/cc/tile_manager.h
@@ -59,7 +59,9 @@ class CC_EXPORT ManagedTileState {
   std::list<skia::LazyPixelRef*> pending_pixel_refs;
 
   // Ephemeral state, valid only during Manage.
-  TileManagerBin bin;
+  TileManagerBin bin[NUM_TREES];
+  // Bin used to determine raster priority.
+  TileManagerBin raster_bin;
   TileResolution resolution;
   float time_to_needed_in_seconds;
 };
@@ -81,7 +83,10 @@ class CC_EXPORT TileManager {
   void ManageTiles();
   void CheckForCompletedSetPixels();
 
-  void renderingStats(RenderingStats* stats);
+  void GetRenderingStats(RenderingStats* stats);
+
+  int GetTilesInBinCount(TileManagerBin bin, WhichTree tree);
+  int GetDrawableTilesInBinCount(TileManagerBin bin, WhichTree tree);
 
  protected:
   // Methods called by Tile
@@ -91,6 +96,7 @@ class CC_EXPORT TileManager {
   void WillModifyTilePriority(Tile*, WhichTree, const TilePriority& new_priority);
 
  private:
+  void ResetBinCounts();
   void AssignGpuMemoryToTiles();
   void FreeResourcesForTile(Tile*);
   void ScheduleManageTiles();
@@ -116,6 +122,9 @@ class CC_EXPORT TileManager {
 
   GlobalStateThatImpactsTilePriority global_state_;
 
+  int tiles_in_bin_count_[NUM_BINS][NUM_TREES];
+  int drawable_tiles_in_bin_count_[NUM_BINS][NUM_TREES];
+
   typedef std::vector<Tile*> TileVector;
   TileVector tiles_;
   TileVector tiles_that_need_to_be_rasterized_;