Prepare for per frame did{Start,Stop}Loading calls

content/renderer/load_progress_tracker.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/load_progress_tracker.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "content/common/view_messages.h"
 #include "content/renderer/render_view_impl.h"
 
 namespace content {
 namespace {
 
 const int kMinimumDelayBetweenUpdatesMS = 100;
 
+// This matches what blink's ProgrssTracker has traditionally used for a
+// minmum progress value.

[Charlie Reis, 2014/03/11 21:51:12]

nit: minimum

+const double kMinimumProgress = 0.1;
+
 }
 
 LoadProgressTracker::LoadProgressTracker(RenderViewImpl* render_view)
     : render_view_(render_view),
-      tracked_frame_(NULL),
-      progress_(0.0),
+      total_progress_(0.0),
       weak_factory_(this) {
 }
 
 LoadProgressTracker::~LoadProgressTracker() {
 }
 
-void LoadProgressTracker::DidStopLoading() {
-  if (!tracked_frame_)
+void LoadProgressTracker::DidStartLoading(int frame_routing_id) {
+  progresses_[frame_routing_id] = kMinimumProgress;
+  SendChangeLoadProgress();
+}
+
+void LoadProgressTracker::DidStopLoading(int frame_routing_id) {
+  if (progresses_.find(frame_routing_id) == progresses_.end())
     return;
 
-  // Load stopped while we were still tracking load.  Make sure we notify the
-  // browser that load is complete.
-  progress_ = 1.0;
+  // Load stopped while we were still tracking load.  Make sure we update
+  // progress based on this frame's completion.
+  progresses_[frame_routing_id] = 1.0;
   SendChangeLoadProgress();
   // Then we clean-up our states.
-  ResetStates();
+  if (total_progress_ == 1.0)
+    ResetStates();
 }
 
-void LoadProgressTracker::DidChangeLoadProgress(blink::WebFrame* frame,
+void LoadProgressTracker::DidChangeLoadProgress(int frame_routing_id,
                                                 double progress) {
-  if (tracked_frame_ && frame != tracked_frame_)
-    return;
-
-  if (!tracked_frame_)
-    tracked_frame_ = frame;
-
-  progress_ = progress;
+  progresses_[frame_routing_id] = progress;
 
   // We send the progress change to the browser immediately for the first and
   // last updates.  Also, since the message loop may be pretty busy when a page
   // is loaded, it might not execute a posted task in a timely manner so we make
   // sure to immediately send progress report if enough time has passed.
   base::TimeDelta min_delay =
       base::TimeDelta::FromMilliseconds(kMinimumDelayBetweenUpdatesMS);
   if (progress == 1.0 || last_time_progress_sent_.is_null() ||
       base::TimeTicks::Now() - last_time_progress_sent_ >
       min_delay) {

[Charlie Reis, 2014/03/11 21:51:12]

nit: I know this isn't yours, but can you add 4 spaces to this indent, since
it's an unfinished expression?  Right now it looks like another line of the
conditional.

[Nate Chapin, 2014/03/11 22:09:59]

I don't see why there's an extra line there, min_delay fits on the previous
line.

     // If there is a pending task to send progress, it is now obsolete.
     weak_factory_.InvalidateWeakPtrs();
     SendChangeLoadProgress();
-    if (progress == 1.0)
+    if (total_progress_ == 1.0)
       ResetStates();
     return;
   }
 
   if (weak_factory_.HasWeakPtrs())
     return;
 
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&LoadProgressTracker::SendChangeLoadProgress,
                  weak_factory_.GetWeakPtr()),
       min_delay);
 }
 
 void LoadProgressTracker::SendChangeLoadProgress() {
   last_time_progress_sent_ = base::TimeTicks::Now();
+  double progress = 0.0;
+  unsigned frameCount = 0;
+  ProgressMap::iterator end = progresses_.end();
+  for (ProgressMap::iterator it = progresses_.begin(); it != end; ++it) {
+    progress += it->second;
+    frameCount++;
+  }
+  progress /= frameCount;

[Charlie Reis, 2014/03/11 21:51:12]

This is crying out to divide by zero if progresses_ is ever empty.  :)

[Nate Chapin, 2014/03/11 22:09:59]

That shouldn't be possible, but...yeah, let's just add an early exit.

+  DCHECK(progress <= 1.0);
+
+  if (progress <= total_progress_)
+    return;
+  total_progress_ = progress;
+
   render_view_->Send(
       new ViewHostMsg_DidChangeLoadProgress(render_view_->routing_id(),
-                                            progress_));
+                                            progress));
 }
 
 void LoadProgressTracker::ResetStates() {
-  tracked_frame_ = NULL;
-  progress_ = 0.0;
+  progresses_.clear();
+  total_progress_ = 0.0;
   weak_factory_.InvalidateWeakPtrs();
   last_time_progress_sent_ = base::TimeTicks();
 }
 
 }  // namespace content