Teach navigation throttles how to cancel requests in WillProcessResponse.

content/browser/frame_host/navigation_request.cc

Index: content/browser/frame_host/navigation_request.cc
diff --git a/content/browser/frame_host/navigation_request.cc b/content/browser/frame_host/navigation_request.cc
index df0f7a1e7b7128331b36debd5882b31dd4f37bd5..0aab9b7a5c3e6aa652869b9c43bfca3c77cf59da 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -259,8 +259,10 @@ void NavigationRequest::OnRequestRedirected(
 void NavigationRequest::OnResponseStarted(
     const scoped_refptr<ResourceResponse>& response,
     scoped_ptr<StreamHandle> body) {
-  DCHECK(state_ == STARTED);
+  DCHECK(state_ == STARTED && !response_ && !body_);
   state_ = RESPONSE_STARTED;
+  response_ = response.get();
+  body_ = std::move(body);
 
   // Update the service worker params of the request params.
   request_params_.should_create_service_worker =
@@ -272,8 +274,10 @@ void NavigationRequest::OnResponseStarted(
             ->service_worker_provider_host_id();
   }
 
-  frame_tree_node_->navigator()->CommitNavigation(
-      frame_tree_node_, response.get(), std::move(body));
+  navigation_handle_->WillProcessResponse(
+      response->head.headers,
+      base::Bind(&NavigationRequest::OnResponseChecksComplete,
+                 base::Unretained(this)));
 }
 
 void NavigationRequest::OnRequestFailed(bool has_stale_copy_in_cache,
@@ -330,6 +334,22 @@ void NavigationRequest::OnRedirectChecksComplete(
   navigation_handle_->DidRedirectNavigation(common_params_.url);
 }
 
+void NavigationRequest::OnResponseChecksComplete(
+    NavigationThrottle::ThrottleCheckResult result) {
+  CHECK(result != NavigationThrottle::DEFER);
+
+  // Abort the request if needed. This will destroy the NavigationRequest.
+  if (result == NavigationThrottle::CANCEL_AND_IGNORE ||
+      result == NavigationThrottle::CANCEL) {
+    // TODO(clamy): distinguish between CANCEL and CANCEL_AND_IGNORE.
+    frame_tree_node_->ResetNavigationRequest(false);
+    return;
+  }
+
+  frame_tree_node_->navigator()->CommitNavigation(
+      frame_tree_node_, response_.get(), std::move(body_));
+}
+
 void NavigationRequest::InitializeServiceWorkerHandleIfNeeded() {
   // Only initialize the ServiceWorkerNavigationHandle if it can be created for
   // this frame.