First draft of TileManager's tile prioritzation system

cc/tile_manager.h

Index: cc/tile_manager.h
diff --git a/cc/tile_manager.h b/cc/tile_manager.h
index 3446c335b3260f0b8f9f4b72db618f6962b7b928..8f6bf8811b1f3083bb496c46a48e0bf08cf7971a 100644
--- a/cc/tile_manager.h
+++ b/cc/tile_manager.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/values.h"
+#include "cc/layer_tree_host_impl.h"
 #include "cc/tile_priority.h"
 
 namespace cc {
@@ -24,6 +25,36 @@ class TileManagerClient {
   virtual ~TileManagerClient() {}
 };
 
+// Tile manager classifying tiles into a few basic
+// bins:
+enum TileManagerBin {
+  NOW_BIN = 0, // Needed ASAP.
+  SOON_BIN = 1, // Impl-side version of prepainting.
+  EVENTUALLY_BIN = 2, // Nice to have, if we've got memory and time.
+  NEVER_BIN = 3, // Dont bother.
+  NUM_BINS = 4
+};
+
+// This is state that is specific to a tile that is
+// managed by the TileManager.
+class ManagedTileState {
+ public:
+  ManagedTileState()
+    : can_use_gpu_memory(false)
+    , resource_id(0)
+    , resource_id_can_be_freed(0) {}
+
+  // Persisted state: valid all the time.
+  bool can_use_gpu_memory;
+  ResourceProvider::ResourceId resource_id;
+  bool resource_id_can_be_freed;
+
+  // Ephemeral state, valid only during Manage.
+  TileManagerBin bin;
+  TileResolution resolution;
+  float time_to_needed_in_seconds;
+};
+
 // This class manages tiles, deciding which should get rasterized and which
 // should no longer have any memory assigned to them. Tile objects are "owned"
 // by layers; they automatically register with the manager when they are
@@ -38,19 +69,24 @@ class TileManager {
 
  protected:
   // Methods called by Tile
-  void DidCreateTileVersion(TileVersion*);
-  void WillModifyTileVersionPriority(TileVersion*, const TilePriority& new_priority);
-  void DidDeleteTileVersion(TileVersion*);
+  friend class Tile;
+  void RegisterTile(Tile*);
+  void UnregisterTile(Tile*);
+  void WillModifyTilePriority(Tile*, WhichTree, const TilePriority& new_priority);
 
  private:
-  friend class Tile;
+  void FreeResourcesForTile(Tile*);
   void ScheduleManageTiles();
+  void ScheduleMorePaintingJobs();
 
   TileManagerClient* client_;
   bool manage_tiles_pending_;
 
   GlobalStateThatImpactsTilePriority global_state_;
-  std::vector<TileVersion*> tile_versions_;
+
+  typedef std::vector<Tile*> TileVector;
+  TileVector tiles_;
+  TileVector tiles_that_need_to_be_painted_;
 };
 
 }  // namespace cc