Add a way to cancel deferred navigations in NavigationHandle

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 93d9887eed0109858c360b3ac98c8b1f21d3dc7d..0fa8adf29875200f0874ae8ff90e031f309a41ae 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -288,7 +288,9 @@ void NavigationRequest::OnStartChecksComplete(
   CHECK(result != NavigationThrottle::DEFER);
 
   // Abort the request if needed. This will destroy the NavigationRequest.
-  if (result == NavigationThrottle::CANCEL_AND_IGNORE) {
+  if (result == NavigationThrottle::CANCEL_AND_IGNORE ||
+      result == NavigationThrottle::CANCEL) {
+    // TODO(clamy): distinguish between CANCEL and CANCEL_AND_IGNORE.

[nasko, 2015/11/04 22:44:27]

What would be the practical difference?

[clamy, 2015/11/05 15:52:23]

It's different at the ResourceController level. Apparently CANCEL_AND_IGNORE
results in a flag was_ignored_by_handler being set to true, and this is passed
around through blink and back to the browser, where it is a parameter to
WCO::DidFailProvisionalLoad. From code search, it does not seem that this
parameter is used anywhere though. Maybe we'll be able to remove it? (unless it
is used somewhere on Android).

[nasko, 2015/11/06 17:31:59]

If it isn't used, removing it will be great! I honestly have no idea what this
"ignored by handler" implies, so it is a good candidate for deleting if
possible.

     frame_tree_node_->ResetNavigationRequest(false);
     return;
   }
@@ -303,7 +305,9 @@ void NavigationRequest::OnRedirectChecksComplete(
   CHECK(result != NavigationThrottle::DEFER);
 
   // Abort the request if needed. This will destroy the NavigationRequest.
-  if (result == NavigationThrottle::CANCEL_AND_IGNORE) {
+  if (result == NavigationThrottle::CANCEL_AND_IGNORE ||
+      result == NavigationThrottle::CANCEL) {
+    // TODO(clamy): distinguish between CANCEL and CANCEL_AND_IGNORE.
     frame_tree_node_->ResetNavigationRequest(false);
     return;
   }