Move Framebuffer invalidation into the impl.

BUG=angle:841

Change-Id: Ibcf58c4f676491f3b2582198c6cf9fd4a7a38b42
Reviewed-on: https://chromium-review.googlesource.com/232392
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/renderer/FramebufferImpl.h b/src/libANGLE/renderer/FramebufferImpl.h
index ae7be4b..b8bc7f3 100644
--- a/src/libANGLE/renderer/FramebufferImpl.h
+++ b/src/libANGLE/renderer/FramebufferImpl.h
@@ -9,8 +9,15 @@
 #ifndef LIBANGLE_RENDERER_FRAMBUFFERIMPL_H_
 #define LIBANGLE_RENDERER_FRAMBUFFERIMPL_H_
 
+#include "libANGLE/Error.h"
+
 #include "angle_gl.h"
 
+namespace gl
+{
+struct Rectangle;
+}
+
 namespace rx
 {
 
@@ -30,6 +37,9 @@
 {
   public:
     virtual ~FramebufferImpl() {};
+
+    virtual gl::Error invalidate(size_t count, const GLenum *attachments) = 0;
+    virtual gl::Error invalidateSub(size_t count, const GLenum *attachments, const gl::Rectangle &area) = 0;
 };
 
 }