cc: Add tiling raster tile iterators.

cc/resources/tile.h

Index: cc/resources/tile.h
diff --git a/cc/resources/tile.h b/cc/resources/tile.h
index c0ed843cc6c3fcea5c49066609bb73e331568776..138cad5f52dcd0b466a8131782a3026166c21178 100644
--- a/cc/resources/tile.h
+++ b/cc/resources/tile.h
@@ -79,6 +79,18 @@ class CC_EXPORT Tile : public RefCountedManaged<Tile> {
     return !!(flags_ & USE_GPU_RASTERIZATION);
   }
 
+  bool NeedsRasterForMode(RasterMode mode) const {
+    return !managed_state_.tile_versions[mode].IsReadyToDraw();
+  }
+
+  bool HasResources() const {
+    for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
+      if (managed_state_.tile_versions[mode].has_resource())
+        return true;
+    }
+    return false;
+  }
+
   scoped_ptr<base::Value> AsValue() const;
 
   inline bool IsReadyToDraw() const {
@@ -116,6 +128,12 @@ class CC_EXPORT Tile : public RefCountedManaged<Tile> {
 
   size_t GPUMemoryUsageInBytes() const;
 
+  gfx::Size size() const { return tile_size_.size(); }
+
+  RasterMode DetermineRasterModeForTree(WhichTree tree) const;
+  RasterMode DetermineOverallRasterMode() const;
+
+  // Functionality used in tests.
   RasterMode GetRasterModeForTesting() const {
     return managed_state().raster_mode;
   }
@@ -123,8 +141,6 @@ class CC_EXPORT Tile : public RefCountedManaged<Tile> {
     return managed_state_.tile_versions[mode];
   }
 
-  gfx::Size size() const { return tile_size_.size(); }
-
  private:
   friend class TileManager;
   friend class PrioritizedTileSet;
@@ -146,6 +162,7 @@ class CC_EXPORT Tile : public RefCountedManaged<Tile> {
 
   ManagedTileState& managed_state() { return managed_state_; }
   const ManagedTileState& managed_state() const { return managed_state_; }
+  RasterMode DetermineRasterModeForResolution(TileResolution resolution) const;
 
   TileManager* tile_manager_;
   scoped_refptr<PicturePileImpl> picture_pile_;