Add a new ozone switch to enable surfaceless output mode.

ui/ozone/public/surface_factory_ozone.h

 // Copyright (c) 2013 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.
 
 #ifndef UI_OZONE_PUBLIC_SURFACE_FACTORY_OZONE_H_
 #define UI_OZONE_PUBLIC_SURFACE_FACTORY_OZONE_H_
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/native_library.h"
@@ skipping 72 matching lines @@
   virtual intptr_t GetNativeDisplay();
 
   // Create SurfaceOzoneEGL for the specified gfx::AcceleratedWidget.
   //
   // Note: When used from content, this is called in the GPU process. The
   // platform must support creation of SurfaceOzoneEGL from the GPU process
   // using only the handle contained in gfx::AcceleratedWidget.
   virtual scoped_ptr<SurfaceOzoneEGL> CreateEGLSurfaceForWidget(
       gfx::AcceleratedWidget widget);
 
+  // Create an EGL surface that isn't backed by any buffers, and is used
+  // for overlay-only displays. This will return NULL if this mode is
+  // not supported.
+  virtual scoped_ptr<SurfaceOzoneEGL> CreateEmptyEGLSurfaceForWidget(

[dnicoara, 2014/08/07 14:48:21]

nit: I don't like naming it Empty. Surfaceless is what it is referred to in
other parts of the code and how EGL refers to it.

+      gfx::AcceleratedWidget widget);
+
   // Create SurfaceOzoneCanvas for the specified gfx::AcceleratedWidget.
   //
   // Note: The platform must support creation of SurfaceOzoneCanvas from the
   // Browser Process using only the handle contained in gfx::AcceleratedWidget.
   virtual scoped_ptr<SurfaceOzoneCanvas> CreateCanvasForWidget(
       gfx::AcceleratedWidget widget);
 
   // Sets up GL bindings for the native surface. Takes two callback parameters
   // that allow Ozone to register the GL bindings.
   virtual bool LoadEGLGLES2Bindings(
@@ skipping 21 matching lines @@
   // overlay-only mode.
   virtual bool CanShowPrimaryPlaneAsOverlay();
 
  private:
   static SurfaceFactoryOzone* impl_;  // not owned
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_SURFACE_FACTORY_OZONE_H_