Allow GLSurface to indicate that it supports a specific extension.

ui/gfx/gl/gl_surface_egl.cc

 // Copyright (c) 2011 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/gfx/gl/gl_surface_egl.h"
 
 #include "build/build_config.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/angle/include/EGL/egl.h"
@@ skipping 244 matching lines @@
     return gfx::Size();
   }
 
   return gfx::Size(width, height);
 }
 
 EGLSurface NativeViewGLSurfaceEGL::GetHandle() {
   return surface_;
 }
 
-bool NativeViewGLSurfaceEGL::SupportsPostSubBuffer() {
-  return supports_post_sub_buffer_;
+std::string NativeViewGLSurfaceEGL::GetExtensions() {
+  std::string extensions = GLSurface::GetExtensions();
+  if (supports_post_sub_buffer_) {
+    extensions += extensions.empty() ? "" : " ";
+    extensions += "GL_CHROMIUM_post_sub_buffer";
+  }
+  return extensions;
 }
 
 bool NativeViewGLSurfaceEGL::PostSubBuffer(
     int x, int y, int width, int height) {
   DCHECK(supports_post_sub_buffer_);
   if (!eglPostSubBufferNV(GetDisplay(), surface_, x, y, width, height)) {
     VLOG(1) << "eglPostSubBufferNV failed with error "
             << GetLastEGLErrorString();
     return false;
   }
@@ skipping 83 matching lines @@
                                    GetHandle(),
                                    EGL_D3D_TEXTURE_2D_SHARE_HANDLE_ANGLE,
                                    &handle)) {
     return NULL;
   }
 
   return handle;
 }
 
 }  // namespace gfx