Add DIRECT_COMPOSITION GpuMemoryBuffer type.

ui/gl/gl_image.h

Index: ui/gl/gl_image.h
diff --git a/ui/gl/gl_image.h b/ui/gl/gl_image.h
index 3e34bbf32b0be0c3e8ec001de8c1493c8c90bc5a..fc30151c26be60eaeb0b3d0e0f5621abc413d766 100644
--- a/ui/gl/gl_image.h
+++ b/ui/gl/gl_image.h
@@ -26,6 +26,7 @@ class ProcessMemoryDump;
 }
 
 namespace gl {
+class GLSurface;
 
 // Encapsulates an image that can be bound and/or copied to a texture, hiding
 // platform specific management.
@@ -93,9 +94,11 @@ class GL_EXPORT GLImage : public base::RefCounted<GLImage> {
   virtual bool EmulatingRGB() const;
 
   // An identifier for subclasses. Necessary for safe downcasting.
-  enum class Type { NONE, MEMORY, IOSURFACE, DXGI_IMAGE };
+  enum class Type { NONE, MEMORY, IOSURFACE, DXGI_IMAGE, DIRECT_COMPOSITION };

[reveman, 2017/06/14 21:35:59]

This type of downcasting is an indication that're not able to create the proper
API and abstraction for what we're trying to do. I think we should strive
towards being able to remove this. Is this really needed in the direct
composition case?

[jbauman, 2017/06/14 22:18:17]

I guess I could have windows-only GetSwapChain() and GetDCompositionSurface()
methods that would be implemented only by the DirectCompositionChildSurfaceWin,
if you want.

   virtual Type GetType() const;
 
+  virtual scoped_refptr<GLSurface> GetSurface();

[reveman, 2017/06/14 21:35:59]

How is this suppose to be used? Can we do something similar to
ScheduleOverlayPlane instead?

[jbauman, 2017/06/14 22:18:17]

This is actually going to be used to draw into the texture. The
DirectComposition surfaces can't really be used as FBOs, so we'll need to have a
new GL command that makes a GLImage current on the context. This will retrieve
the GLSurface that will actually be made current.

+
  protected:
   virtual ~GLImage() {}