Make surface GetFormat pure virtual, add missing overrides.

ui/gl/gl_surface_glx.cc

 // Copyright (c) 2012 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_glx.h"
 
 extern "C" {
 #include <X11/Xlib.h>
 }
 #include <memory>
@@ skipping 598 matching lines @@
 bool NativeViewGLSurfaceGLX::SupportsPostSubBuffer() {
   return g_driver_glx.ext.b_GLX_MESA_copy_sub_buffer;
 }
 
 void* NativeViewGLSurfaceGLX::GetConfig() {
   if (!config_)
     config_ = GetConfigForWindow(g_display, window_);
   return config_;
 }
 
+GLSurfaceFormat NativeViewGLSurfaceGLX::GetFormat() {
+  return GLSurfaceFormat();
+}
+
 unsigned long NativeViewGLSurfaceGLX::GetCompatibilityKey() {
   return visual_id_;
 }
 
 gfx::SwapResult NativeViewGLSurfaceGLX::PostSubBuffer(int x,
                                                       int y,
                                                       int width,
                                                       int height) {
   DCHECK(g_driver_glx.ext.b_GLX_MESA_copy_sub_buffer);
   glXCopySubBufferMESA(g_display, GetDrawableHandle(), x, y, width, height);
@@ skipping 73 matching lines @@
 void* UnmappedNativeViewGLSurfaceGLX::GetHandle() {
   return reinterpret_cast<void*>(glx_window_);
 }
 
 void* UnmappedNativeViewGLSurfaceGLX::GetConfig() {
   if (!config_)
     config_ = GetConfigForWindow(g_display, window_);
   return config_;
 }
 
+GLSurfaceFormat UnmappedNativeViewGLSurfaceGLX::GetFormat() {
+  return GLSurfaceFormat();
+}
+
 unsigned long UnmappedNativeViewGLSurfaceGLX::GetCompatibilityKey() {
   return XVisualIDFromVisual(g_visual);
 }
 
 UnmappedNativeViewGLSurfaceGLX::~UnmappedNativeViewGLSurfaceGLX() {
   Destroy();
 }
 
 }  // namespace gl