PlzNavigate: Call DidStartLoading and DidStopLoading.

content/browser/frame_host/frame_tree_node.cc

Index: content/browser/frame_host/frame_tree_node.cc
diff --git a/content/browser/frame_host/frame_tree_node.cc b/content/browser/frame_host/frame_tree_node.cc
index cabc819f4322201f2a42b9a5881e457628fcf2f2..5960f2aa0a6815a2db32841344ab4d15eedb60f5 100644
--- a/content/browser/frame_host/frame_tree_node.cc
+++ b/content/browser/frame_host/frame_tree_node.cc
@@ -166,10 +166,15 @@ bool FrameTreeNode::IsLoading() const {
       render_manager_.pending_frame_host();
 
   DCHECK(current_frame_host);
-  // TODO(fdegans): Change the implementation logic for PlzNavigate once
-  // DidStartLoading and DidStopLoading are properly called.
-  if (pending_frame_host && pending_frame_host->is_loading())
-    return true;
+
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    if (navigation_request_)
+      return true;
+  } else {
+    if (pending_frame_host && pending_frame_host->is_loading())
+      return true;
+  }
   return current_frame_host->is_loading();
 }
 
@@ -185,7 +190,17 @@ void FrameTreeNode::SetNavigationRequest(
   CHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
   ResetNavigationRequest(false);
-  // TODO(clamy): perform the StartLoading logic here.
+
+  // Force the throbber to start to keep it in sync with what is happening in
+  // the UI. Blink doesn't send throb notifications for JavaScript URLs, so it
+  // is not done here either.
+  if (!navigation_request->common_params().url.SchemeIs(
+          url::kJavaScriptScheme)) {
+    // TODO(fdegans): Check if this is a same-document navigation and set the
+    // proper argument.
+    DidStartLoading(true);
+  }
+
   navigation_request_ = navigation_request.Pass();
 }
 
@@ -196,11 +211,13 @@ void FrameTreeNode::ResetNavigationRequest(bool is_commit) {
   // cleanup performed since the navigation is still ongoing. If the reset

[Charlie Reis, 2015/04/28 23:10:04]

What navigation tasks are still ongoing after commit?  I generally consider that
to be the end of navigation.  Is it loading state?  (Just wondering if we can
clarify this comment.)

[Fabrice (no longer in Chrome), 2015/04/29 09:54:43]

Yes it is the loading state. I rephrased the comment a bit. WDYT

   // corresponds to a cancelation, the RenderFrameHostManager should clean up
   // any speculative RenderFrameHost it created for the navigation.
-  if (navigation_request_ && !is_commit) {
-    // TODO(clamy): perform the StopLoading logic.
+  if (navigation_request_) {
+    navigation_request_.reset();
+    if (is_commit)
+      return;
+    DidStopLoading();
     render_manager_.CleanUpNavigation();
   }
-  navigation_request_.reset();
 }
 
 bool FrameTreeNode::has_started_loading() const {