Fix for LoginFeedbackTest.Basic broken by recent change.

content/browser/media/capture/aura_window_capture_machine.cc

 // Copyright 2013 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/browser/media/capture/aura_window_capture_machine.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/logging.h"
@@ skipping 106 matching lines @@
       window_host->compositor()->RemoveObserver(this);
     desktop_window_->RemoveObserver(this);
     desktop_window_ = NULL;
     cursor_renderer_.reset();
   }
 
   callback.Run();
 }
 
 void AuraWindowCaptureMachine::MaybeCaptureForRefresh() {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  Capture(false);
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&AuraWindowCaptureMachine::Capture,
+                 // Use of Unretained() is safe here since this task must run
+                 // before InternalStop().
+                 base::Unretained(this),

[mcasas, 2016/04/07 19:12:57]

Actually, since |this| pointer would be used
on UI thread, you could use
weak_factory_.GetWeakPtr()
right?

https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/me...

[miu, 2016/04/07 19:55:31]

tl;dr: It doesn't really matter, but the raw pointer is less overhead.

I had considered this.  However, we can easily reason that it's not needed:

1. Since we know MaybeCaptureForRefresh() must be called on the same thread as
Stop(), and will never be called after Stop(); then we know the tasks posted to
run on the UI thread will be sequenced such that the raw pointer will always be
valid.

2. If instead we post a task using a WeakPtr, the tasks running on the UI thread
will still have the same execution sequence.  The weak pointer could never be
invalidated in the meantime (because InternalStop() always has to run after the
task posted here).  So, using the WeakPtr doesn't add any value, but *does* add
overhead.

+                 false));
 }
 
 void AuraWindowCaptureMachine::SetWindow(aura::Window* window) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   DCHECK(!desktop_window_);
   desktop_window_ = window;
   cursor_renderer_.reset(new CursorRendererAura(window, kCursorAlwaysEnabled));
 
   // Start observing window events.
@@ skipping 213 matching lines @@
   // TODO(miu): The CopyOutputRequest should be made earlier, at WillCommit().
   // http://crbug.com/492839
   BrowserThread::PostTask(
       BrowserThread::UI,
       FROM_HERE,
       base::Bind(&AuraWindowCaptureMachine::Capture, weak_factory_.GetWeakPtr(),
                  true));
 }
 
 }  // namespace content