Switch DRM platform to using a separate thread

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

Index: ui/ozone/platform/drm/gpu/gbm_buffer.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer.cc b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
index 3d07983a8ee5baaa4e9269684efd229b5cc01eeb..e2e53f6a8e473c1b726b79add8c6576e2dfdf9ba 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
@@ -14,8 +14,10 @@
 #include "base/trace_event/trace_event.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/native_pixmap_handle_ozone.h"
+#include "ui/ozone/platform/drm/gpu/drm_thread.h"
 #include "ui/ozone/platform/drm/gpu/drm_window.h"
 #include "ui/ozone/platform/drm/gpu/gbm_device.h"
+#include "ui/ozone/platform/drm/gpu/proxy_helpers.h"
 
 namespace ui {
 
@@ -72,9 +74,8 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
 }
 
 GbmPixmap::GbmPixmap(const scoped_refptr<GbmBuffer>& buffer,
-                     ScreenManager* screen_manager)
-    : buffer_(buffer), screen_manager_(screen_manager) {
-}
+                     DrmThread* drm_thread)
+    : buffer_(buffer), drm_thread_(drm_thread) {}
 
 bool GbmPixmap::Initialize() {
   // We want to use the GBM API because it's going to call into libdrm
@@ -145,8 +146,16 @@ bool GbmPixmap::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
     }
   }
 
-  screen_manager_->GetWindow(widget)->QueueOverlayPlane(OverlayPlane(
-      buffer_, plane_z_order, plane_transform, display_bounds, crop_rect));
+  if (widget != cached_widget_) {
+    cached_widget_ = widget;
+    cached_window_ = drm_thread_->GetWindow(cached_widget_);

[spang, 2015/09/18 00:46:25]

How about:

(1) store window_id -> Surface map in GbmSurfaceFactory
(2) queue overlays on GbmSurfaceless
(3) send the whole stack in OnSwapBuffersAsync

It could be done as a preliminary step.

[dnicoara, 2015/09/18 17:43:08]

Acknowledged.

+  }
+
+  drm_thread_->task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(&DrmWindow::QueueOverlayPlane, cached_window_,
+                 OverlayPlane(buffer_, plane_z_order, plane_transform,
+                              display_bounds, crop_rect)));
   return true;
 }