cc: Add checker-imaging support to TileManager.

cc/layers/picture_layer_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 "cc/layers/picture_layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1351 matching lines @@
 
 bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
   return !layer_tree_impl()->IsRecycleTree();
 }
 
 bool PictureLayerImpl::HasValidTilePriorities() const {
   return IsOnActiveOrPendingTree() &&
          is_drawn_render_surface_layer_list_member();
 }
 
+void PictureLayerImpl::InvalidateRegionForImages(
+    const std::unordered_set<ImageId>& images_to_invalidate) {
+  InvalidationRegion image_invalidation;
+  for (auto image_id : images_to_invalidate) {
+    image_invalidation.Union(raster_source_->GetRectForImage(image_id));
+  }
+
+  if (image_invalidation.IsEmpty())

[vmpstr, 2017/02/10 19:25:42]

Should we just check if (images_to_invalidate.empty()) and return earlier?

I also want the trace to capture the loop when we union the regions, so if we do
that check and then move the trace above the for loop then you can use
TRACE_EVENT_BEGIN0/TRACE_EVENT_END1 to record the invalidation (you can see the
trace in TileManager::AssignGpuMemoryToTiles as an example)

[Khushal, 2017/02/10 22:09:19]

Good point. That check should be in LayerTreeImpl so we don't iterate through
the layers if we don't need to. I doubt that would be the case often anyway. The
empty invalidation here will most likely be from the fact that the image was
from a different layer, or may be it was removed in the next frame...
How is it now?

+    return;
+
+  Region invalidation;
+  image_invalidation.Swap(&invalidation);
+  TRACE_EVENT1("cc", "PictureLayerImpl::InvalidatingForImages", "invalidation",
+               invalidation.ToString());
+  invalidation_.Union(invalidation);
+  tilings_->UpdateTilingsForImplSideInvalidation(invalidation);
+  SetNeedsPushProperties();
+}
+
 }  // namespace cc