Abort if BrowserMainLoops fails to start a browser thread

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 2a34b24ef02542b39966e2ccab814cafb4a13b00..18c682d007bf31f827863b7eb4f948fc18c9de74 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -1046,8 +1046,11 @@ int BrowserMainLoop::BrowserThreadsStarted() {
     TRACE_EVENT0(
         "startup",
         "BrowserMainLoop::BrowserThreadsStarted::InitUserInputMonitor");
-    user_input_monitor_ = media::UserInputMonitor::Create(
-        io_thread_->message_loop_proxy(), main_thread_->message_loop_proxy());
+    if (io_thread_->message_loop_proxy().get() != NULL &&

[Charlie Reis, 2014/09/11 23:10:30]

If we want to confirm that the cause of this crash is early shutdown, then
perhaps a better way is to check Thread::IsRunning() here instead of doing a
null check on message_loop_proxy.  Then we'll still notice (via crash reports)
if some other unknown issue is present.

[jiayl, 2014/09/11 23:55:37]

I tested it with your suggestion, but IsRunning() is false even during normal
startup when the TaskRunner is not NULL.

+        main_thread_->message_loop_proxy().get() != NULL) {
+      user_input_monitor_ = media::UserInputMonitor::Create(
+          io_thread_->message_loop_proxy(), main_thread_->message_loop_proxy());

[Charlie Reis, 2014/09/11 23:10:30]

Can this use task_runner() instead of message_loop_proxy()?  I noticed that the
latter is deprecated according to thread.h, and the Create call already has the
right contract for it.

[jiayl, 2014/09/11 23:55:37]

Will do.

+    }
   }
 
   {