Switch DRM platform to using a separate thread

ui/ozone/platform/drm/gpu/drm_window.cc

 // Copyright 2014 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 "ui/ozone/platform/drm/gpu/drm_window.h"
 
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkDevice.h"
@@ skipping 108 matching lines @@
   cursor_location_ = location;
 
   if (controller_)
     controller_->MoveCursor(location);
 }
 
 void DrmWindow::QueueOverlayPlane(const OverlayPlane& plane) {
   pending_planes_.push_back(plane);
 }
 
-bool DrmWindow::SchedulePageFlip(const SwapCompletionCallback& callback) {
+void DrmWindow::SchedulePageFlip(const SwapCompletionCallback& callback) {
   if (force_buffer_reallocation_) {
     // Clear pending planes otherwise the next call to queue planes will just
     // add on top.
     pending_planes_.clear();
     force_buffer_reallocation_ = false;
     callback.Run(gfx::SwapResult::SWAP_NAK_RECREATE_BUFFERS);
-    return true;
+    return;
   }
 
   last_submitted_planes_.clear();
   last_submitted_planes_.swap(pending_planes_);
 
   if (controller_) {
-    return controller_->SchedulePageFlip(last_submitted_planes_,
-                                         false /* test_only */, callback);
+    if (!controller_->SchedulePageFlip(last_submitted_planes_,
+                                       false /* test_only */, callback))
+      callback.Run(gfx::SwapResult::SWAP_FAILED);
+  } else {
+    callback.Run(gfx::SwapResult::SWAP_ACK);
   }
-
-  callback.Run(gfx::SwapResult::SWAP_ACK);
-  return true;
 }
 
 bool DrmWindow::TestPageFlip(const std::vector<OverlayCheck_Params>& overlays,
                              ScanoutBufferGenerator* buffer_generator) {
   if (!controller_)
     return true;
   for (const auto& overlay : overlays) {
     // It is possible that the cc rect we get actually falls off the edge of
     // the screen. Usually this is prevented via things like status bars
     // blocking overlaying or cc clipping it, but in case it wasn't properly
@@ skipping 114 matching lines @@
       if (!cursor_buffers_[i]->Initialize(
               info, false /* should_register_framebuffer */)) {
         LOG(FATAL) << "Failed to initialize cursor buffer";
         return;
       }
     }
   }
 }
 
 }  // namespace ui