Update content/ to use scoped_refptr<T>::get() rather than implicit "operator T*"

content/browser/renderer_host/media/web_contents_tracker.cc

Index: content/browser/renderer_host/media/web_contents_tracker.cc
diff --git a/content/browser/renderer_host/media/web_contents_tracker.cc b/content/browser/renderer_host/media/web_contents_tracker.cc
index 68e76c503bbcf5786f29f0bd0eddbbf127b31f5e..a13dc12c33147aa85c7a54847459721504e47a48 100644
--- a/content/browser/renderer_host/media/web_contents_tracker.cc
+++ b/content/browser/renderer_host/media/web_contents_tracker.cc
@@ -20,10 +20,10 @@ WebContentsTracker::~WebContentsTracker() {
 
 void WebContentsTracker::Start(int render_process_id, int render_view_id,
                                const ChangeCallback& callback) {
-  DCHECK(!message_loop_ || message_loop_->BelongsToCurrentThread());
+  DCHECK(!message_loop_.get() || message_loop_->BelongsToCurrentThread());
 
   message_loop_ = base::MessageLoopProxy::current();
-  DCHECK(message_loop_);
+  DCHECK(message_loop_.get());
   callback_ = callback;
 
   BrowserThread::PostTask(