Teach navigation throttles how to cancel requests in WillProcessResponse.

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 <utility>
 
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/frame_host/navigator.h"
@@ skipping 261 matching lines @@
   complete_callback_ = callback;
 
   // Notify each throttle of the request.
   NavigationThrottle::ThrottleCheckResult result = CheckWillRedirectRequest();
 
   // If the navigation is not deferred, run the callback.
   if (result != NavigationThrottle::DEFER)
     RunCompleteCallback(result);
 }
 
+void NavigationHandleImpl::WillProcessResponse(
+    scoped_refptr<net::HttpResponseHeaders> response_headers,
+    const ThrottleChecksFinishedCallback& callback) {
+  response_headers_ = response_headers;
+  state_ = WILL_PROCESS_RESPONSE;
+  complete_callback_ = callback;
+
+  // Notify each throttle of the response.
+  NavigationThrottle::ThrottleCheckResult result = CheckWillProcessResponse();
+
+  DCHECK(result != NavigationThrottle::DEFER);

[clamy, 2016/01/25 16:36:21]

This should match the other checks:
// If the navigation is not deferred, run the callback.
if (result != NavigationThrottle::DEFER)
  RunCompleteCallback(result);

Since we're introducing the API, some user of the API could decide to defer the
navigation at that step.

[Mike West, 2016/01/26 09:41:41]

Done.

+  RunCompleteCallback(result);
+}
+
 void NavigationHandleImpl::DidRedirectNavigation(const GURL& new_url) {
   url_ = new_url;
   GetDelegate()->DidRedirectNavigation(this);
 }
 
 void NavigationHandleImpl::ReadyToCommitNavigation(
     RenderFrameHostImpl* render_frame_host,
     scoped_refptr<net::HttpResponseHeaders> response_headers) {
   DCHECK(!render_frame_host_ || render_frame_host_ == render_frame_host);
   render_frame_host_ = render_frame_host;
@@ skipping 70 matching lines @@
 
       default:
         NOTREACHED();
     }
   }
   next_index_ = 0;
   state_ = WILL_REDIRECT_REQUEST;
   return NavigationThrottle::PROCEED;
 }
 
+NavigationThrottle::ThrottleCheckResult
+NavigationHandleImpl::CheckWillProcessResponse() {
+  DCHECK(state_ == WILL_PROCESS_RESPONSE && next_index_ == 0);
+  for (size_t i = next_index_; i < throttles_.size(); ++i) {
+    NavigationThrottle::ThrottleCheckResult result =
+        throttles_[i]->WillProcessResponse();
+    switch (result) {
+      case NavigationThrottle::PROCEED:
+        continue;
+
+      case NavigationThrottle::CANCEL:
+      case NavigationThrottle::CANCEL_AND_IGNORE:
+        state_ = CANCELING;
+        return result;
+
+      case NavigationThrottle::DEFER:

[clamy, 2016/01/25 16:36:21]

Since we're introducing it in the public API, we need to handle that case as
well, as in the function just above.

[Mike West, 2016/01/26 09:41:41]

Done.

+        NOTREACHED();
+    }
+  }
+  state_ = WILL_PROCESS_RESPONSE;
+  return NavigationThrottle::PROCEED;
+}
+
 void NavigationHandleImpl::RunCompleteCallback(
     NavigationThrottle::ThrottleCheckResult result) {
   DCHECK(result != NavigationThrottle::DEFER);
-  if (!complete_callback_.is_null())
-    complete_callback_.Run(result);
 
+  ThrottleChecksFinishedCallback callback = complete_callback_;
   complete_callback_.Reset();
+
+  if (!callback.is_null())
+    callback.Run(result);
+
+  // No code after running the calback, as it might result in our destruction.
 }
 
 }  // namespace content