Allow building mojo_shell and non-graphical apps/services on a Mac

ui/gl/gl_surface_mac.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.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 25 matching lines @@
  public:
   explicit NoOpGLSurface(const gfx::Size& size,
                          const gfx::SurfaceConfiguration conf)
       : GLSurface(conf),
         size_(size) {}
 
   // Implement GLSurface.
   bool Initialize() override { return true; }
   void Destroy() override {}
   bool IsOffscreen() override { return true; }
-  bool SwapBuffers() override {
+  gfx::SwapResult SwapBuffers() override {
     NOTREACHED() << "Cannot call SwapBuffers on a NoOpGLSurface.";
-    return false;
+    return gfx::SwapResult::SWAP_FAILED;
   }
   gfx::Size GetSize() override { return size_; }
   void* GetHandle() override { return NULL; }
   void* GetDisplay() override { return NULL; }
   bool IsSurfaceless() const override { return true; }
 
  protected:
   ~NoOpGLSurface() override {}
 
  private:
@@ skipping 92 matching lines @@
     }
     case kGLImplementationMockGL:
       return new GLSurfaceStub(conf);
     default:
       NOTREACHED();
       return NULL;
   }
 }
 
 }  // namespace gfx