Make surface GetFormat pure virtual, add missing overrides.

ui/gl/gl_surface_glx.h

 // 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.
 
 #ifndef UI_GL_GL_SURFACE_GLX_H_
 #define UI_GL_GL_SURFACE_GLX_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 54 matching lines @@
   void Destroy() override;
   bool Resize(const gfx::Size& size,
               float scale_factor,
               bool has_alpha) override;
   bool IsOffscreen() override;
   gfx::SwapResult SwapBuffers() override;
   gfx::Size GetSize() override;
   void* GetHandle() override;
   bool SupportsPostSubBuffer() override;
   void* GetConfig() override;
+  GLSurfaceFormat GetFormat() override;
   unsigned long GetCompatibilityKey() override;
   gfx::SwapResult PostSubBuffer(int x, int y, int width, int height) override;
   gfx::VSyncProvider* GetVSyncProvider() override;
   VisualID GetVisualID() const { return visual_id_; }
 
  protected:
   ~NativeViewGLSurfaceGLX() override;
 
   // Handle registering and unregistering for Expose events.
   virtual void RegisterEvents() = 0;
@@ skipping 35 matching lines @@
   explicit UnmappedNativeViewGLSurfaceGLX(const gfx::Size& size);
 
   // Implement GLSurfaceGLX.
   bool Initialize(GLSurfaceFormat format) override;
   void Destroy() override;
   bool IsOffscreen() override;
   gfx::SwapResult SwapBuffers() override;
   gfx::Size GetSize() override;
   void* GetHandle() override;
   void* GetConfig() override;
+  GLSurfaceFormat GetFormat() override;
   unsigned long GetCompatibilityKey() override;
 
  protected:
   ~UnmappedNativeViewGLSurfaceGLX() override;
 
  private:
   gfx::Size size_;
   GLXFBConfig config_;
   // Unmapped dummy window, used to provide a compatible surface.
   gfx::AcceleratedWidget window_;
 
   // GLXDrawable for the window.
   GLXWindow glx_window_;
 
   DISALLOW_COPY_AND_ASSIGN(UnmappedNativeViewGLSurfaceGLX);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_SURFACE_GLX_H_