Augment message_loop with ability for custom UI message pumps (issue 576536)

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index e84765a0f7a7e022764ce0db1509f572745c51a0..88f75e91e5b6863ae260a3530a0bd803da095809 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -398,7 +398,7 @@ MessageLoop::MessageLoop(Type type, MessagePumpFactoryCallback pump_factory)
           new internal::MessageLoopTaskRunner(incoming_task_queue_)),
       task_runner_(unbound_task_runner_) {
   // If type is TYPE_CUSTOM non-null pump_factory must be given.
-  DCHECK_EQ(type_ == TYPE_CUSTOM, !pump_factory_.is_null());
+  DCHECK(type_ != TYPE_CUSTOM || !pump_factory_.is_null());
 }
 
 void MessageLoop::BindToCurrentThread() {
@@ -684,6 +684,10 @@ void MessageLoop::ReleaseSoonInternal(
 //------------------------------------------------------------------------------
 // MessageLoopForUI
 
+MessageLoopForUI::MessageLoopForUI(scoped_ptr<MessagePump> pump)
+    : MessageLoop(TYPE_UI, Bind(&ReturnPump, Passed(&pump))) {
+}
+
 #if defined(OS_ANDROID)
 void MessageLoopForUI::Start() {
   // No Histogram support for UI message loop as it is managed by Java side