Revert of Remove DCHECK_IMPLIES/CHECK_IMPLIES.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 459 matching lines @@
                                   page_scale,
                                   duration.InSecondsF());
   }
 
   SetNeedsAnimate();
   client_->SetNeedsCommitOnImplThread();
   client_->RenewTreePriority();
 }
 
 void LayerTreeHostImpl::SetNeedsAnimateInput() {
-  DCHECK(!IsCurrentlyScrollingInnerViewport() ||
-         !settings_.ignore_root_layer_flings);
+  DCHECK_IMPLIES(IsCurrentlyScrollingInnerViewport(),
+                 !settings_.ignore_root_layer_flings);
   SetNeedsAnimate();
 }
 
 bool LayerTreeHostImpl::IsCurrentlyScrollingInnerViewport() const {
   LayerImpl* scrolling_layer = CurrentlyScrollingLayer();
   if (!scrolling_layer)
     return false;
   return scrolling_layer == InnerViewportScrollLayer();
 }
 
@@ skipping 520 matching lines @@
                    "draw_result", draw_result, "missing tiles",
                    num_missing_tiles);
 
   // Draw has to be successful to not drop the copy request layer.
   // When we have a copy request for a layer, we need to draw even if there
   // would be animating checkerboards, because failing under those conditions
   // triggers a new main frame, which may cause the copy request layer to be
   // destroyed.
   // TODO(weiliangc): Test copy request w/ output surface recreation. Would
   // trigger this DCHECK.
-  DCHECK(!have_copy_request || draw_result == DRAW_SUCCESS);
+  DCHECK_IMPLIES(have_copy_request, draw_result == DRAW_SUCCESS);
 
   return draw_result;
 }
 
 void LayerTreeHostImpl::MainThreadHasStoppedFlinging() {
   top_controls_manager_->MainThreadHasStoppedFlinging();
   if (input_handler_client_)
     input_handler_client_->MainThreadHasStoppedFlinging();
 }
 
@@ skipping 2623 matching lines @@
   return task_runner_provider_->HasImplThread();
 }
 
 bool LayerTreeHostImpl::CommitToActiveTree() const {
   // In single threaded mode we skip the pending tree and commit directly to the
   // active tree.
   return !task_runner_provider_->HasImplThread();
 }
 
 }  // namespace cc