Relanding "Add apk for running content_browsertests"

Revert "Revert 179189"

This reverts commit 5844ab0c6a41cc9d306f8c355cc7ceb5e290cbb1.

Original CL:https://codereview.chromium.org/12047068/
was reverted as we failed to update the bot scripts with the new package
name for content_shell_apk

TBR=mark@chromium.org,jam@chromium.org
BUG=138275


Review URL: https://chromiumcodereview.appspot.com/12091033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@179428 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 4d4eb5babc558ccddc09168f66970905ed0204d4
diff --git a/base/message_loop.cc b/base/message_loop.cc
index 5428026..0a6bf6c 100644
--- a/base/message_loop.cc
+++ b/base/message_loop.cc
@@ -251,9 +251,12 @@
 }
 
 // static
-void MessageLoop::InitMessagePumpForUIFactory(MessagePumpFactory* factory) {
-  DCHECK(!message_pump_for_ui_factory_);
+bool MessageLoop::InitMessagePumpForUIFactory(MessagePumpFactory* factory) {
+  if (message_pump_for_ui_factory_)
+    return false;
+
   message_pump_for_ui_factory_ = factory;
+  return true;
 }
 
 void MessageLoop::AddDestructionObserver(