Revert of Remove DCHECK_IMPLIES/CHECK_IMPLIES.

cc/tiles/picture_layer_tiling.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/tiles/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
@@ skipping 266 matching lines @@
     DCHECK_EQ(after_bottom, before_bottom + 1);
     for (int i = before_left; i <= before_right; ++i) {
       Tile::CreateInfo info = CreateInfoForTile(i, after_bottom);
       if (ShouldCreateTileAt(info))
         CreateTile(info);
     }
   }
 }
 
 void PictureLayerTiling::Invalidate(const Region& layer_invalidation) {
-  DCHECK(tree_ != ACTIVE_TREE || !client_->GetPendingOrActiveTwinTiling(this));
+  DCHECK_IMPLIES(tree_ == ACTIVE_TREE,
+                 !client_->GetPendingOrActiveTwinTiling(this));
   RemoveTilesInRegion(layer_invalidation, true /* recreate tiles */);
 }
 
 void PictureLayerTiling::RemoveTilesInRegion(const Region& layer_invalidation,
                                              bool recreate_tiles) {
   // We only invalidate the active tiling when it's orphaned: it has no pending
   // twin, so it's slated for removal in the future.
   if (live_tiles_rect_.IsEmpty())
     return;
   // Pick 16 for the size of the SmallMap before it promotes to a hash_map.
@@ skipping 380 matching lines @@
       }
     }
   }
   DCHECK_EQ(visible_rect_in_content_space.IsEmpty(), eventually_rect.IsEmpty());
 
   // Now we have an empty visible/eventually rect if it's not useful and a
   // non-empty one if it is. We can compute the final eventually rect.
   eventually_rect =
       tiling_data_.ExpandRectIgnoringBordersToTileBounds(eventually_rect);
 
-  DCHECK(eventually_rect.IsEmpty() ||
-         gfx::Rect(tiling_size()).Contains(eventually_rect))
+  DCHECK_IMPLIES(!eventually_rect.IsEmpty(),
+                 gfx::Rect(tiling_size()).Contains(eventually_rect))
       << "tiling_size: " << tiling_size().ToString()
       << " eventually_rect: " << eventually_rect.ToString();
 
   if (tiling_size().IsEmpty()) {
     UpdateVisibleRectHistory(current_frame_time_in_seconds,
                              visible_rect_in_content_space);
     last_viewport_in_layer_space_ = viewport_in_layer_space;
     return false;
   }
 
@@ skipping 329 matching lines @@
 size_t PictureLayerTiling::GPUMemoryUsageInBytes() const {
   size_t amount = 0;
   for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) {
     const Tile* tile = it->second;
     amount += tile->GPUMemoryUsageInBytes();
   }
   return amount;
 }
 
 }  // namespace cc