Make a fairer combined message loop

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 9e33a426eb9f1241be625c25aee1a1585898c6fc..a0ce91fa4b3b39bb34c4893261cd8eafb336d4aa 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -143,7 +143,8 @@ MessageLoop::MessageLoop(Type type)
 #if defined(OS_WIN)
       os_modal_loop_(false),
 #endif  // OS_WIN
-      next_sequence_num_(0) {
+      next_sequence_num_(0),
+      always_notify_pump_(false) {
   DCHECK(!current()) << "should only have one message loop per thread";
   lazy_tls_ptr.Pointer()->Set(this);
 
@@ -186,6 +187,7 @@ MessageLoop::MessageLoop(Type type)
     DCHECK_EQ(TYPE_DEFAULT, type_);
     pump_ = new MessagePumpDefault();
   }
+  always_notify_pump_ = pump_->NeedsScheduleWorkPerTask();

[awong, 2013/07/03 19:09:22]

Always_notify_pump_ seems to effectively be a platform constant. It almost seems
cleaner to just keep the #if define(OS_ANDROID) in this file and avoid
introducing the new variable + method.

[Kristian Monsen, 2013/07/03 21:20:03]

I had a CL doing this locally, was not sure which one was best. I kind of liked
what you are describing, but one of the reviewer thought this was better.

One nice side effect of keeping it local is that reverting will be cleaner ...

 }
 
 MessageLoop::~MessageLoop() {
@@ -624,7 +626,9 @@ bool MessageLoop::AddToIncomingQueue(PendingTask* pending_task,
     bool was_empty = incoming_queue_.empty();
     incoming_queue_.push(*pending_task);
     pending_task->task.Reset();
-    if (!was_empty)
+    // The Android UI message loop needs to get notified each time
+    // a task is added to the incoming queue

[awong, 2013/07/03 19:09:22]

nit: Please end sentences with a period.

[Kristian Monsen, 2013/07/03 21:20:03]

Done.

+    if (!was_empty && !always_notify_pump_)
       return true;  // Someone else should have started the sub-pump.
 
     pump = pump_;