Implement the logic to kick off image decoding jobs for TileManager

cc/picture_pile_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/debug/trace_event.h"
 #include "cc/picture_pile_impl.h"
 #include "cc/rendering_stats.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkSize.h"
 #include "ui/gfx/rect_conversions.h"
@@ skipping 61 matching lines @@
 
     SkISize deviceSize = canvas->getDeviceSize();
     stats->totalPixelsRasterized += deviceSize.width() * deviceSize.height();
   }
   canvas->restore();
 
   stats->totalRasterizeTimeInSeconds += (base::TimeTicks::Now() -
                                          rasterizeBeginTime).InSecondsF();
 }
 
+void PicturePileImpl::GatherPixelRefs(
+    const gfx::Rect& rect, std::list<skia::LazyPixelRef*>& pixel_refs) {
+  std::list<skia::LazyPixelRef*> result;
+  for (PicturePile::Pile::const_iterator i = pile_.begin();
+      i != pile_.end(); ++i) {
+    (*i)->GatherPixelRefs(rect, result);
+    pixel_refs.splice(pixel_refs.end(), result);
+  }
+}
+
 }  // namespace cc