Increase priority of raster threads on Android.

base/threading/platform_thread_win.cc

 // Copyright (c) 2012 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.
 
 #include "base/threading/platform_thread.h"
 
 #include "base/debug/alias.h"
 #include "base/debug/profiler.h"
 #include "base/logging.h"
 #include "base/threading/thread_id_name_manager.h"
@@ skipping 222 matching lines @@
 // static
 void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
                                        ThreadPriority priority) {
   DCHECK(!handle.is_null());
 
   int desired_priority = THREAD_PRIORITY_ERROR_RETURN;
   switch (priority) {
     case ThreadPriority::BACKGROUND:
       desired_priority = THREAD_PRIORITY_LOWEST;
       break;
+    case ThreadPriority::UI_BACKGROUND:

[no sievers, 2015/06/25 22:52:15]

Now I'm wondering if BELOW_NORMAL is actually a better name than UI_BACKGROUND.
Don't feel strongly though...

[aelias_OOO_until_Jul13, 2015/06/25 23:49:13]

I chose UI_BACKGROUND because the other priority names ("REALTIME_AUDIO") refer
to use cases.  Maybe "UI_BACKGROUND" doesn't communicate the use case that well
though... what do you think about "BACKGROUND_GRAPHICS"?

+      desired_priority = THREAD_PRIORITY_BELOW_NORMAL;
+      break;
     case ThreadPriority::NORMAL:
       desired_priority = THREAD_PRIORITY_NORMAL;
       break;
     case ThreadPriority::DISPLAY:
       desired_priority = THREAD_PRIORITY_ABOVE_NORMAL;
       break;
     case ThreadPriority::REALTIME_AUDIO:
       desired_priority = THREAD_PRIORITY_TIME_CRITICAL;
       break;
     default:
@@ skipping 26 matching lines @@
       return ThreadPriority::REALTIME_AUDIO;
     case THREAD_PRIORITY_ERROR_RETURN:
       DPCHECK(false) << "GetThreadPriority error";  // Falls through.
     default:
       NOTREACHED() << "Unexpected priority: " << priority;
       return ThreadPriority::NORMAL;
   }
 }
 
 }  // namespace base