Implement the logic to kick off image decoding jobs for TileManager

cc/picture_pile_impl.cc

Index: cc/picture_pile_impl.cc
diff --git a/cc/picture_pile_impl.cc b/cc/picture_pile_impl.cc
index f8e56cc1083c31ded307e223609941075d5c0e64..7c8cbd712ec1d94638f7869e80ac5cd3d2a6bfbc 100644
--- a/cc/picture_pile_impl.cc
+++ b/cc/picture_pile_impl.cc
@@ -72,4 +72,14 @@ void PicturePileImpl::Raster(
                                          rasterizeBeginTime).InSecondsF();
 }
 
+void PicturePileImpl::GatherPixelRefs(const gfx::Rect& rect,
+                                      std::vector<SkPixelRef*>& pixel_refs) {
+  for (PicturePile::Pile::const_iterator i = pile_.begin();
+      i != pile_.end(); ++i) {
+    std::vector<SkPixelRef*> result;
+    (*i)->GatherPixelRefs(rect, result);
+    pixel_refs.insert(pixel_refs.end(), result.begin(), result.end());
+  }
+}
+
 }  // namespace cc