Fix segfault when unplugging captured external display

content/browser/media/capture/desktop_capture_device_aura.cc

Index: content/browser/media/capture/desktop_capture_device_aura.cc
diff --git a/content/browser/media/capture/desktop_capture_device_aura.cc b/content/browser/media/capture/desktop_capture_device_aura.cc
index 6b6557f1844058b74dc539b5d6b24289630dbaba..60713dc127b105a901b2f95896fb5dd43f4480a4 100644
--- a/content/browser/media/capture/desktop_capture_device_aura.cc
+++ b/content/browser/media/capture/desktop_capture_device_aura.cc
@@ -235,8 +235,10 @@ void DesktopVideoCaptureMachine::Stop(const base::Closure& callback) {
 
   // Stop observing compositor and window events.
   if (desktop_window_) {
-    if (desktop_window_->GetHost())
-      desktop_window_->GetHost()->compositor()->RemoveObserver(this);
+    aura::WindowTreeHost* wth = desktop_window_->GetHost();

[Sergey Ulanov, 2014/12/12 18:46:53]

Please use a more descriptive name.
From
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#General_Namin...
:
Function names, variable names, and filenames should be descriptive; eschew
abbreviation.

I suggest |window_host|.

+    // In the host destructor the compositor is destroyed before the window.
+    if (wth && wth->compositor())
+      wth->compositor()->RemoveObserver(this);
     desktop_window_->RemoveObserver(this);
     desktop_window_ = NULL;
   }