Allow one-copy task tile worker pool to use compressed textures.

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 <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
@@ skipping 749 matching lines @@
     tile_width = std::min(tile_width, content_bounds.width());
     tile_width = MathUtil::UncheckedRoundUp(tile_width, kTileRoundUp);
     tile_width = std::min(tile_width, default_tile_width);
   }
   if (content_bounds.height() < default_tile_height) {
     tile_height = std::min(tile_height, content_bounds.height());
     tile_height = MathUtil::UncheckedRoundUp(tile_height, kTileRoundUp);
     tile_height = std::min(tile_height, default_tile_height);
   }
 
+  // Ensure that tiles are an even multiple of 4 in size.

[reveman, 2015/12/01 17:27:24]

Unconditionally use MathUtil::UncheckedRoundUp(tile_.., 4)?

Also, can you define something like kTileMinimalAlignment with a comment
explaining why we need it instead of just using the magic value of 4?

[christiank, 2015/12/02 16:18:14]

Done.

+  if (tile_width % 4 != 0 || tile_height % 4 != 0) {
+    // Round the size up to the nearest multiple of four.
+    tile_width = 4 * std::ceil(static_cast<float>(tile_width) / 4);
+    tile_height = 4 * std::ceil(static_cast<float>(tile_height) / 4);
+  }
+
   // Under no circumstance should we be larger than the max texture size.
   tile_width = std::min(tile_width, max_texture_size);
   tile_height = std::min(tile_height, max_texture_size);
   return gfx::Size(tile_width, tile_height);
 }
 
 void PictureLayerImpl::GetContentsResourceId(ResourceId* resource_id,
                                              gfx::Size* resource_size) const {
   // The bounds and the pile size may differ if the pile wasn't updated (ie.
   // PictureLayer::Update didn't happen). In that case the pile will be empty.
@@ skipping 460 matching lines @@
 
 bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
   return !layer_tree_impl()->IsRecycleTree();
 }
 
 bool PictureLayerImpl::HasValidTilePriorities() const {
   return IsOnActiveOrPendingTree() && IsDrawnRenderSurfaceLayerListMember();
 }
 
 }  // namespace cc