cc: Update picture pile on tiles to prevent memory leak

A given PicturePileImpl corresponds to a given main thread frame.  It should go
out of scope when that frame is no longer being used.  Currently, as Tile holds
a ref on PicturePileImpl, it won't go out of scope if the Tile persists, which
could happen if the Tile never gets invalidated.  To prevent this, the
PicturePileImpl on each Tile is updated to the newest version of the
PicturePileImpl when a tree is activated.  This will allow old PicturePileImpls
to be destroyed on a more regular basis.

Raster jobs in flight hold their own ref to a per-thead clone of the
PicturePileImpl, so this will not affect them.  When the job finishes, the
clone will also be destroyed.

R=reveman@chromium.org
BUG=171003


Review URL: https://chromiumcodereview.appspot.com/11953005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@178106 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 0 deletions

diff --git a/cc/tile.h b/cc/tile.h
index 7d41e6a..dcb24e0 100644
--- a/cc/tile.h
+++ b/cc/tile.h
@@ -54,6 +54,10 @@ class CC_EXPORT Tile : public base::RefCounted<Tile> {
   float contents_scale() const { return contents_scale_; }
   gfx::Rect content_rect() const { return content_rect_; }
 
+  void set_picture_pile(scoped_refptr<PicturePileImpl> pile) {
+   picture_pile_ = pile;
+  }
+
  private:
   // Methods called by by tile manager.
   friend class TileManager;