Revert of Remove DCHECK_IMPLIES/CHECK_IMPLIES.

content/browser/frame_host/navigation_handle_impl.cc

 // Copyright 2015 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 "content/browser/frame_host/navigation_handle_impl.h"
 
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/frame_host/navigator.h"
 #include "content/browser/frame_host/navigator_delegate.h"
 #include "content/public/browser/content_browser_client.h"
@@ skipping 230 matching lines @@
     RenderFrameHostImpl* render_frame_host) {
   CHECK(!render_frame_host_);
   render_frame_host_ = render_frame_host;
   state_ = READY_TO_COMMIT;
   GetDelegate()->ReadyToCommitNavigation(this);
 }
 
 void NavigationHandleImpl::DidCommitNavigation(
     bool same_page,
     RenderFrameHostImpl* render_frame_host) {
-  CHECK(!render_frame_host_ || render_frame_host_ == render_frame_host);
+  CHECK_IMPLIES(render_frame_host_, render_frame_host_ == render_frame_host);
   is_same_page_ = same_page;
   render_frame_host_ = render_frame_host;
   state_ = net_error_code_ == net::OK ? DID_COMMIT : DID_COMMIT_ERROR_PAGE;
 }
 
 NavigationThrottle::ThrottleCheckResult
 NavigationHandleImpl::CheckWillStartRequest() {
   DCHECK(state_ == WILL_SEND_REQUEST || state_ == DEFERRING_START);
-  DCHECK(state_ != WILL_SEND_REQUEST || next_index_ == 0);
-  DCHECK(state_ != DEFERRING_START || next_index_ != 0);
+  DCHECK_IMPLIES(state_ == WILL_SEND_REQUEST, next_index_ == 0);
+  DCHECK_IMPLIES(state_ == DEFERRING_START, next_index_ != 0);
   for (size_t i = next_index_; i < throttles_.size(); ++i) {
     NavigationThrottle::ThrottleCheckResult result =
         throttles_[i]->WillStartRequest();
     switch (result) {
       case NavigationThrottle::PROCEED:
         continue;
 
       case NavigationThrottle::CANCEL_AND_IGNORE:
         return result;
 
       case NavigationThrottle::DEFER:
         state_ = DEFERRING_START;
         next_index_ = i + 1;
         return result;
 
       default:
         NOTREACHED();
     }
   }
   next_index_ = 0;
   state_ = WILL_SEND_REQUEST;
   return NavigationThrottle::PROCEED;
 }
 
 NavigationThrottle::ThrottleCheckResult
 NavigationHandleImpl::CheckWillRedirectRequest() {
   DCHECK(state_ == WILL_REDIRECT_REQUEST || state_ == DEFERRING_REDIRECT);
-  DCHECK(state_ != WILL_REDIRECT_REQUEST || next_index_ == 0);
-  DCHECK(state_ != DEFERRING_REDIRECT || next_index_ != 0);
+  DCHECK_IMPLIES(state_ == WILL_REDIRECT_REQUEST, next_index_ == 0);
+  DCHECK_IMPLIES(state_ == DEFERRING_REDIRECT, next_index_ != 0);
   for (size_t i = next_index_; i < throttles_.size(); ++i) {
     NavigationThrottle::ThrottleCheckResult result =
         throttles_[i]->WillRedirectRequest();
     switch (result) {
       case NavigationThrottle::PROCEED:
         continue;
 
       case NavigationThrottle::CANCEL_AND_IGNORE:
         return result;
 
       case NavigationThrottle::DEFER:
         state_ = DEFERRING_REDIRECT;
         next_index_ = i + 1;
         return result;
 
       default:
         NOTREACHED();
     }
   }
   next_index_ = 0;
   state_ = WILL_REDIRECT_REQUEST;
   return NavigationThrottle::PROCEED;
 }
 
 }  // namespace content