Partial swap implementation for surfaceless

ui/gl/gl_surface_ozone.cc

Index: ui/gl/gl_surface_ozone.cc
diff --git a/ui/gl/gl_surface_ozone.cc b/ui/gl/gl_surface_ozone.cc
index 0c30c20ba0a578206ae85103637afcfea4c94b18..7a602979e1cad5fa3420dbea4b4e41f08a7ee33d 100644
--- a/ui/gl/gl_surface_ozone.cc
+++ b/ui/gl/gl_surface_ozone.cc
@@ -138,6 +138,13 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
   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() {