cc: Force an update on tile size after viewport resize

cc/layers/picture_layer_impl.h

 // 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.
 
 #ifndef CC_LAYERS_PICTURE_LAYER_IMPL_H_
 #define CC_LAYERS_PICTURE_LAYER_IMPL_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 153 matching lines @@
 
   // Any draw properties derived from |transform|, |viewport|, and |clip|
   // parameters in LayerTreeHostImpl::SetExternalDrawConstraints are not valid
   // for prioritizing tiles during resourceless software draws. This is because
   // resourceless software draws can have wildly different transforms/viewports
   // from regular draws. Save a copy of the required draw properties of the last
   // frame that has a valid viewport for prioritizing tiles.
   gfx::Rect visible_rect_for_tile_priority_;
   gfx::Rect viewport_rect_for_tile_priority_in_content_space_;
 
+  // Keep track of the last viewport rect. If it changes, we need to ensure that
+  // the texture size is correct in the tiling.
+  gfx::Size last_viewport_size_;
+
   // List of tilings that were used last time we appended quads. This can be
   // used as an optimization not to remove tilings if they are still being
   // drawn. Note that accessing this vector should only be done in the context
   // of comparing pointers, since objects pointed to are not guaranteed to
   // exist.
   std::vector<PictureLayerTiling*> last_append_quads_tilings_;
 
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_