PlzNavigate: Updated navigation cancel policy for renderer-initiated requests.

Now the navigation cancellation logic should conform to what has been described
in the "PlzNavigate: Navigation cancellation" design document [1]. Added some
new tests to exercise the cancellation cases described in the document.

Note: This is being developed on top of http://crrev.com/912833002.

[1] https://docs.google.com/a/chromium.org/document/d/1lO7_fgppFTDd8PSQfIb888z7vODcw2Sc8r7h5Rbiwcg/edit#

BUG=376014

Review URL: https://codereview.chromium.org/914223002

Cr-Commit-Position: refs/heads/master@{#317083}

content/browser/frame_host/navigation_request.h

@@ -78,6 +78,8 @@ class CONTENT_EXPORT NavigationRequest : public NavigationURLLoaderDelegate {
 
   const CommonNavigationParams& common_params() const { return common_params_; }
 
+  const BeginNavigationParams& begin_params() const { return begin_params_; }
+
   const CommitNavigationParams& commit_params() const { return commit_params_; }
 
   NavigationURLLoader* loader_for_testing() const { return loader_.get(); }

content/browser/frame_host/navigator_impl.cc

@@ -703,14 +703,27 @@ void NavigatorImpl::OnBeginNavigation(
     const CommonNavigationParams& common_params,
     const BeginNavigationParams& begin_params,
     scoped_refptr<ResourceRequestBody> body) {
+  // This is a renderer-initiated navigation.
   CHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
   DCHECK(frame_tree_node);
 
-  // This is a renderer-initiated navigation, so generate a new
-  // NavigationRequest and store it in the map.
-  // TODO(clamy): Renderer-initiated navigations should not always cancel the
-  // current one.
+  NavigationRequest* ongoing_navigation_request =
+      navigation_request_map_.get(frame_tree_node->frame_tree_node_id());
+
+  // The renderer-initiated navigation request is ignored iff a) there is an
+  // ongoing request b) which is browser or user-initiated and c) the renderer
+  // request is not user-initiated.
+  if (ongoing_navigation_request &&
+      (ongoing_navigation_request->browser_initiated() ||
+       ongoing_navigation_request->begin_params().has_user_gesture) &&
+      !begin_params.has_user_gesture) {
+    return;
+  }
+
+  // In all other cases the current navigation, if any, is canceled and a new
+  // NavigationRequest is created and stored in the map. Actual cancellation
+  // happens when the existing request map entry is replaced and destroyed.
   scoped_ptr<NavigationRequest> navigation_request =
       NavigationRequest::CreateRendererInitiated(
           frame_tree_node, common_params, begin_params, body);

content/test/test_render_frame_host.cc

@@ -187,9 +187,10 @@ void TestRenderFrameHost::SendNavigateWithParameters(
   OnDidCommitProvisionalLoad(msg);
 }
 
-void TestRenderFrameHost::SendBeginNavigationWithURL(const GURL& url) {
-  BeginNavigationParams begin_params(
-      "GET", std::string(), net::LOAD_NORMAL, false);
+void TestRenderFrameHost::SendBeginNavigationWithURL(const GURL& url,
+                                                     bool has_user_gesture) {
+  BeginNavigationParams begin_params("GET", std::string(), net::LOAD_NORMAL,
+                                     has_user_gesture);
   CommonNavigationParams common_params;
   common_params.url = url;
   common_params.referrer = Referrer(GURL(), blink::WebReferrerPolicyDefault);
@@ -215,9 +216,9 @@ void TestRenderFrameHost::PrepareForCommit(const GURL& url) {
       static_cast<NavigatorImpl*>(frame_tree_node_->navigator())
           ->GetNavigationRequestForNodeForTesting(frame_tree_node_);
 
-  // We are simulating a renderer-initiated navigation.
+  // We are simulating a renderer-initiated user-initiated navigation.
   if (!request) {
-    SendBeginNavigationWithURL(url);
+    SendBeginNavigationWithURL(url, true);
     request = static_cast<NavigatorImpl*>(frame_tree_node_->navigator())
         ->GetNavigationRequestForNodeForTesting(frame_tree_node_);
   }

content/test/test_render_frame_host.h

@@ -85,7 +85,7 @@ class TestRenderFrameHost : public RenderFrameHostImpl,
       int response_code,
       const base::FilePath* file_path_for_history_item,
       const std::vector<GURL>& redirects);
-  void SendBeginNavigationWithURL(const GURL& url);
+  void SendBeginNavigationWithURL(const GURL& url, bool has_user_gesture);
 
   void DidDisownOpener();