Add a way to cancel deferred navigations in NavigationHandle

content/browser/frame_host/navigation_handle_impl.h

Index: content/browser/frame_host/navigation_handle_impl.h
diff --git a/content/browser/frame_host/navigation_handle_impl.h b/content/browser/frame_host/navigation_handle_impl.h
index 6f46707108e531ceac132639638d387611e5710f..a72e774e78dad5b6e13a1258daa021a19e521e27 100644
--- a/content/browser/frame_host/navigation_handle_impl.h
+++ b/content/browser/frame_host/navigation_handle_impl.h
@@ -76,6 +76,8 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
   bool HasCommitted() override;
   bool IsErrorPage() override;
   void Resume() override;
+  void CancelDeferredNavigation(
+      NavigationThrottle::ThrottleCheckResult result) override;
   void RegisterThrottleForTesting(
       scoped_ptr<NavigationThrottle> navigation_throttle) override;
   NavigationThrottle::ThrottleCheckResult CallWillStartRequestForTesting(
@@ -156,6 +158,7 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
     DEFERRING_START,
     WILL_REDIRECT_REQUEST,
     DEFERRING_REDIRECT,
+    CANCELING,
     READY_TO_COMMIT,
     DID_COMMIT,
     DID_COMMIT_ERROR_PAGE,
@@ -167,6 +170,10 @@ class CONTENT_EXPORT NavigationHandleImpl : public NavigationHandle {
   NavigationThrottle::ThrottleCheckResult CheckWillStartRequest();
   NavigationThrottle::ThrottleCheckResult CheckWillRedirectRequest();
 
+  // Helper function to run and reset the |complete_callback_|. This marks the
+  // end of a round of NavigationThrottleChecks.
+  void RunCompleteCallback(NavigationThrottle::ThrottleCheckResult result);
+
   // Used in tests.
   State state() const { return state_; }