Partial swap implementation for surfaceless

ui/gl/gl_surface_ozone.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/gl/gl_surface.h"
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gl/gl_context.h"
@@ skipping 120 matching lines @@
                                     GLImage* image,
                                     const Rect& bounds_rect,
                                     const RectF& crop_rect) OVERRIDE {
     return image->ScheduleOverlayPlane(
         widget_, z_order, transform, bounds_rect, crop_rect);
   }
   virtual bool IsOffscreen() OVERRIDE { return false; }
   virtual VSyncProvider* GetVSyncProvider() OVERRIDE {
     return vsync_provider_.get();
   }
+  virtual bool SupportsPostSubBuffer() OVERRIDE { return true; }
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE {
+    // The actual sub buffer handling is handled at higher layers. We need to
+    // return true to SupportsPostSubBuffer to enable it, but we should never
+    // actually get the sub-buffer swap.
+    return false;

[piman, 2014/09/17 20:47:18]

drive-by: This is weird. Why not simply have PostSubBuffer call SwapBuffers and
not having to worry about this at a higher level?

Truth is, what we would really want is neither SwapBuffer nor PostSubBuffer but
a new "CommitPlanes" or something. But I don't think we really need this extra
complexity at this point.

[achaulk, 2014/09/17 21:01:08]

That's also another possibility

[alexst (slow to review), 2014/09/18 16:08:29]

Made a wrong comment about ignoring what comes here, we should call SwapBuffers
instead once we propagate damage to the reflector.

+  }
 
  private:
   virtual ~GLSurfaceOzoneSurfaceless() {
     Destroy();  // EGL surface must be destroyed before SurfaceOzone
   }
 
   // The native surface. Deleting this is allowed to free the EGLNativeWindow.
   scoped_ptr<ui::SurfaceOzoneEGL> ozone_surface_;
   AcceleratedWidget widget_;
   scoped_ptr<VSyncProvider> vsync_provider_;
@@ skipping 90 matching lines @@
       NOTREACHED();
       return NULL;
   }
 }
 
 EGLNativeDisplayType GetPlatformDefaultEGLNativeDisplay() {
   return ui::SurfaceFactoryOzone::GetInstance()->GetNativeDisplay();
 }
 
 }  // namespace gfx