Encourage reliability of code using browser thread.

content/browser/browser_thread.h

 // Copyright (c) 2011 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.
 
 #ifndef CONTENT_BROWSER_BROWSER_THREAD_H_
 #define CONTENT_BROWSER_BROWSER_THREAD_H_
 #pragma once
 
+#if defined(UNIT_TEST)
+#include "base/logging.h"
+#endif  // UNIT_TEST
 #include "base/synchronization/lock.h"
 #include "base/task.h"
 #include "base/threading/thread.h"
 
 namespace base {
 class MessageLoopProxy;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // BrowserThread
@@ skipping 135 matching lines @@
   // task's stack unwinds.  This would lead to the object destructing on the
   // FILE thread, which often is not what you want (i.e. to unregister from
   // NotificationService, to notify other objects on the creating thread etc).
   template<ID thread>
   struct DeleteOnThread {
     template<typename T>
     static void Destruct(const T* x) {
       if (CurrentlyOn(thread)) {
         delete x;
       } else {
-        DeleteSoon(thread, FROM_HERE, x);
+        if (!DeleteSoon(thread, FROM_HERE, x)) {
+#if defined(UNIT_TEST)
+          // Only logged under unit testing because leaks at shutdown
+          // are acceptable under normal circumstances.
+          LOG(ERROR) << "DeleteSoon failed on thread " << thread;
+#endif  // UNIT_TEST
+        }
       }
     }
   };
 
   // Sample usage:
   // class Foo
   //     : public base::RefCountedThreadSafe<
   //           Foo, BrowserThread::DeleteOnIOThread> {
   //
   // ...
@@ skipping 28 matching lines @@
   static base::Lock lock_;
 
   // An array of the BrowserThread objects.  This array is protected by |lock_|.
   // The threads are not owned by this array.  Typically, the threads are owned
   // on the UI thread by the g_browser_process object.  BrowserThreads remove
   // themselves from this array upon destruction.
   static BrowserThread* browser_threads_[ID_COUNT];
 };
 
 #endif  // CONTENT_BROWSER_BROWSER_THREAD_H_