PlzNavigate: add cancel navigation logic for uncommitted requests

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index 5e0872c30b7469b44c38154fefdba2631c72a852..0d3b26a9c3f4d7d23537122b65acfdc1eaa5c26e 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -571,6 +571,9 @@ void RenderFrameHostManager::OnBeginNavigation(
   // crashed) not to display a sad tab while navigating.
   // TODO(clamy): Spawn a speculative renderer process if we do not have one to
   // use for the navigation.
+
+  // The previous existing NavigationRequest instance will be destroyed at this
+  // point, which might cause the cancellation of that request.
   navigation_request_.reset(new NavigationRequest(
       info, frame_tree_node_->frame_tree_node_id()));
   navigation_request_->BeginNavigation(params.request_body);
@@ -581,6 +584,14 @@ void RenderFrameHostManager::CommitNavigation(
     const NavigationBeforeCommitInfo& info) {
   CHECK(CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
+  DCHECK(navigation_request_.get());
+  // Ignores navigation commits if the request ID doesn't match the current
+  // active request.
+  if (navigation_request_->navigation_request_id() !=
+          info.navigation_request_id) {
+    return;
+  }
+
   // Pick the right RenderFrameHost to commit the navigation.
   SiteInstance* current_instance = render_frame_host_->GetSiteInstance();
   // TODO(clamy): Replace the default values by the right ones. This may require