Refactor the loading tracking logic in WebContentsImpl.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index ed679224852e6b4631a4335b32c695015be47e3e..150c974141425fb9b7171dfcffa2c6ba3fd5dd91 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -120,11 +120,6 @@ namespace content {
 namespace {
 
 const int kMinimumDelayBetweenLoadingUpdatesMS = 100;
-
-// This matches what Blink's ProgressTracker has traditionally used for a
-// minimum progress value.
-const double kMinimumLoadingProgress = 0.1;
-
 const char kDotGoogleDotCom[] = ".google.com";
 
 #if defined(OS_ANDROID)
@@ -163,6 +158,27 @@ bool CollectSites(BrowserContext* context,
   return true;
 }
 
+// Helper function used with FrameTree::ForEach() for retrieving the total
+// loading progress and number of frames in a frame tree.
+bool CollectLoadProgress(double* progress,
+                         int* frame_count,
+                         FrameTreeNode* node) {
+  *progress += node->GetLoadingProgress();
+  (*frame_count)++;
+  return true;
+}
+
+// Helper function used with FrameTree::ForEach() to check if at least one of
+// the nodes is loading.
+bool IsNodeLoading(bool* is_loading, FrameTreeNode* node) {
+  if (node->IsLoading()) {
+    // There is at least one node loading, so abort traversal.
+    *is_loading = true;
+    return false;
+  }
+  return true;
+}
+
 bool ForEachFrameInternal(
     const base::Callback<void(RenderFrameHost*)>& on_frame,
     FrameTreeNode* node) {
@@ -333,7 +349,6 @@ WebContentsImpl::WebContentsImpl(BrowserContext* browser_context,
       waiting_for_response_(false),
       load_state_(net::LOAD_STATE_IDLE, base::string16()),
       loading_total_progress_(0.0),
-      loading_frames_in_progress_(0),
       upload_size_(0),
       upload_position_(0),
       displayed_insecure_content_(false),
@@ -2830,42 +2845,27 @@ void WebContentsImpl::OnDidStartLoading(bool to_different_document) {
 
   RenderFrameHostImpl* rfh =
       static_cast<RenderFrameHostImpl*>(render_frame_message_source_);
-  int64 render_frame_id = rfh->frame_tree_node()->frame_tree_node_id();
 
   // Any main frame load to a new document should reset the load progress, since
   // it will replace the current page and any frames.
   if (to_different_document && !rfh->GetParent()) {
     ResetLoadProgressState();
-    loading_frames_in_progress_ = 0;
-    rfh->frame_tree_node()->set_is_loading(false);
+    rfh->set_is_loading(false);
+    rfh->set_loading_progress(RenderFrameHostImpl::kLoadingProgressNotStarted);
   }
 
-  // It is possible to get multiple calls to OnDidStartLoading that don't have
-  // corresponding calls to OnDidStopLoading:
-  // - With "swappedout://" URLs, this happens when a RenderView gets swapped
-  //   out for a cross-process navigation, and it turns into a placeholder for
-  //   one being rendered in a different process.
-  // - Also, there might be more than one RenderFrameHost sharing the same
-  //   FrameTreeNode (and thus sharing its ID) each sending a start.
-  // - But in the future, once clamy@ moves navigation network requests to the
-  //   browser process, there's a good chance that callbacks about starting and
-  //   stopping will all be handled by the browser. When that happens, there
-  //   should no longer be a start/stop call imbalance. TODO(avi): When this
-  //   future arrives, update this code to not allow this case.
-  if (rfh->frame_tree_node()->is_loading())
-    return;
+  // This method should never be called when the frame is loading.
+  DCHECK(!rfh->is_loading());
 
-  DCHECK_GE(loading_frames_in_progress_, 0);
-  if (loading_frames_in_progress_ == 0)
+  if (!IsFrameTreeLoading())
     DidStartLoading(rfh, to_different_document);
 
-  ++loading_frames_in_progress_;
-  rfh->frame_tree_node()->set_is_loading(true);
+  rfh->set_is_loading(true);
+  rfh->set_loading_progress(RenderFrameHostImpl::kLoadingProgressMinimum);
 
   // Notify the RenderFrameHostManager of the event.
   rfh->frame_tree_node()->render_manager()->OnDidStartLoading();
 
-  loading_progresses_[render_frame_id] = kMinimumLoadingProgress;
   SendLoadProgressChanged();
 }
 
@@ -2875,28 +2875,22 @@ void WebContentsImpl::OnDidStopLoading() {
 
   RenderFrameHostImpl* rfh =
       static_cast<RenderFrameHostImpl*>(render_frame_message_source_);
-  int64 render_frame_id = rfh->frame_tree_node()->frame_tree_node_id();
-  rfh->frame_tree_node()->set_is_loading(false);
 
-  if (loading_progresses_.find(render_frame_id) != loading_progresses_.end()) {
-    // Load stopped while we were still tracking load.  Make sure we update
-    // progress based on this frame's completion.
-    loading_progresses_[render_frame_id] = 1.0;
-    SendLoadProgressChanged();
-    // Then we clean-up our states.
-    if (loading_total_progress_ == 1.0)
-      ResetLoadProgressState();
-  }
+  // This method should never be called when the frame is not loading.
+  DCHECK(rfh->is_loading());
+  rfh->set_is_loading(false);
+  rfh->set_loading_progress(RenderFrameHostImpl::kLoadingProgressDone);
+
+  // Update progress based on this frame's completion.
+  SendLoadProgressChanged();
+  // Then clean-up the states.
+  if (loading_total_progress_ == 1.0)
+    ResetLoadProgressState();
 
   // Notify the RenderFrameHostManager of the event.
   rfh->frame_tree_node()->render_manager()->OnDidStopLoading();
 
-  // TODO(japhet): This should be a DCHECK, but the pdf plugin sometimes
-  // calls DidStopLoading() without a matching DidStartLoading().
-  if (loading_frames_in_progress_ == 0)
-    return;
-  --loading_frames_in_progress_;
-  if (loading_frames_in_progress_ == 0)
+  if (!IsFrameTreeLoading())
     DidStopLoading(rfh);
 }
 
@@ -2906,9 +2900,8 @@ void WebContentsImpl::OnDidChangeLoadProgress(double load_progress) {
 
   RenderFrameHostImpl* rfh =
       static_cast<RenderFrameHostImpl*>(render_frame_message_source_);
-  int64 render_frame_id = rfh->frame_tree_node()->frame_tree_node_id();
 
-  loading_progresses_[render_frame_id] = load_progress;
+  rfh->set_loading_progress(load_progress);
 
   // We notify progress change immediately for the first and last updates.
   // Also, since the message loop may be pretty busy when a page is loaded, it
@@ -3390,14 +3383,10 @@ void WebContentsImpl::SendLoadProgressChanged() {
   double progress = 0.0;
   int frame_count = 0;
 
-  for (LoadingProgressMap::iterator it = loading_progresses_.begin();
-       it != loading_progresses_.end();
-       ++it) {
-    progress += it->second;
-    ++frame_count;
-  }
-  if (frame_count == 0)
-    return;
+  frame_tree_.ForEach(
+      base::Bind(&CollectLoadProgress, &progress, &frame_count));
+  DCHECK_GT(frame_count, 0);
+
   progress /= frame_count;
   DCHECK(progress <= 1.0);
 
@@ -3410,12 +3399,17 @@ void WebContentsImpl::SendLoadProgressChanged() {
 }
 
 void WebContentsImpl::ResetLoadProgressState() {
-  loading_progresses_.clear();

[clamy, 2015/02/26 16:05:00]

As mentionned offline, we want to keep the current behavior intact. Therefore I
think you should replace this line with resetting the load progress of the
current RFH in each FTN to kLoadingProgressNotStarted. Then you would need not
to account for frames with a load progress of not started in the count.

Other option, you add a boolean to the RFH/FTN indicating whether it should be
taken into account in the total load computation. It is reset to false for all
frames there, and set to true when a frame starts loading.

[Fabrice (no longer in Chrome), 2015/02/27 17:45:25]

I like the first option because it fixes a whole bunch of problems, including
some we have with the current implementation. I'm going to do that, thanks a
lot!

   loading_total_progress_ = 0.0;
   loading_weak_factory_.InvalidateWeakPtrs();
   loading_last_progress_update_ = base::TimeTicks();
 }
 
+bool WebContentsImpl::IsFrameTreeLoading() {
+  bool is_loading = false;
+  frame_tree_.ForEach(base::Bind(&IsNodeLoading, &is_loading));
+  return is_loading;
+}
+
 void WebContentsImpl::NotifyViewSwapped(RenderViewHost* old_host,
                                         RenderViewHost* new_host) {
   // After sending out a swap notification, we need to send a disconnect
@@ -3727,7 +3721,6 @@ void WebContentsImpl::RenderViewTerminated(RenderViewHost* rvh,
   // webpage? Once this function is called at a more granular frame level, we
   // probably will need to more granularly reset the state here.
   ResetLoadProgressState();
-  loading_frames_in_progress_ = 0;
 
   FOR_EACH_OBSERVER(WebContentsObserver,
                     observers_,