Revert of Remove DCHECK_IMPLIES/CHECK_IMPLIES.

cc/playback/display_item_list.cc

 // Copyright 2014 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/playback/display_item_list.h"
 
 #include <string>
 
 #include "base/numerics/safe_conversions.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 185 matching lines @@
   DCHECK(ProcessAppendedItemsCalled());
   return approximate_op_count_;
 }
 
 size_t DisplayItemList::ApproximateMemoryUsage() const {
   DCHECK(ProcessAppendedItemsCalled());
   // We double-count in this case. Produce zero to avoid being misleading.
   if (use_cached_picture_ && retain_individual_display_items_)
     return 0;
 
-  DCHECK(!use_cached_picture_ || picture_);
+  DCHECK_IMPLIES(use_cached_picture_, picture_);
 
   size_t memory_usage = sizeof(*this);
 
   // Memory outside this class due to |items_|.
   memory_usage += items_.GetCapacityInBytes() + external_memory_usage_;
 
   // Memory outside this class due to |picture|.
   memory_usage += picture_memory_usage_;
 
   // TODO(jbroman): Does anything else owned by this class substantially
@@ skipping 49 matching lines @@
       TRACE_DISABLED_BY_DEFAULT("devtools.timeline.picture"),
       "cc::DisplayItemList", this,
       TracedDisplayItemList::AsTraceableDisplayItemList(this,
           DisplayItemsTracingEnabled()));
 }
 
 void DisplayItemList::GenerateDiscardableImagesMetadata() {
   DCHECK(ProcessAppendedItemsCalled());
   // This should be only called once, and only after CreateAndCacheSkPicture.
   DCHECK(image_map_.empty());
-  DCHECK(!use_cached_picture_ || picture_);
+  DCHECK_IMPLIES(use_cached_picture_, picture_);
   if (use_cached_picture_ && !picture_->willPlayBackBitmaps())
     return;
 
   // The cached picture is translated by -layer_rect_.origin during record,
   // so we need to offset that back in order to get right positioning for
   // images.
   DiscardableImageMap::ScopedMetadataGenerator generator(
       &image_map_, gfx::Size(layer_rect_.right(), layer_rect_.bottom()));
   Raster(generator.canvas(), nullptr,
          gfx::Rect(layer_rect_.right(), layer_rect_.bottom()), 1.f);
 }
 
 void DisplayItemList::GetDiscardableImagesInRect(
     const gfx::Rect& rect,
     float raster_scale,
     std::vector<DrawImage>* images) {
   image_map_.GetDiscardableImagesInRect(rect, raster_scale, images);
 }
 
 }  // namespace cc