ui: Prefer +/- operators to apply offsets.

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 <string>
+
 #include "base/compiler_specific.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/size.h"
 #include "ui/gl/gl_export.h"
 #include "ui/gl/gl_surface.h"
 
 namespace gfx {
 
 // Base class for GLX surfaces.
@@ skipping 34 matching lines @@
   virtual bool Initialize() OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool Resize(const gfx::Size& size) OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual void* GetHandle() OVERRIDE;
   virtual std::string GetExtensions() OVERRIDE;
   virtual void* GetConfig() OVERRIDE;
   virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
-  virtual bool GetVSyncParameters(base::TimeTicks* timebase,
-                                  base::TimeDelta* interval) OVERRIDE;
+  virtual void GetVSyncParameters(const UpdateVSyncCallback& callback) OVERRIDE;
+
+  class VSyncProvider {
+   public:
+    virtual ~VSyncProvider() { }
+
+    virtual void GetVSyncParameters(
+        const GLSurface::UpdateVSyncCallback& callback) = 0;
+  };
 
  protected:
   NativeViewGLSurfaceGLX();
   virtual ~NativeViewGLSurfaceGLX();
 
   gfx::AcceleratedWidget window_;
 
  private:
   void* config_;
   gfx::Size size_;
 
+  scoped_ptr<VSyncProvider> vsync_provider_;
+
   DISALLOW_COPY_AND_ASSIGN(NativeViewGLSurfaceGLX);
 };
 
 // A surface used to render to an offscreen pbuffer.
 class GL_EXPORT PbufferGLSurfaceGLX : public GLSurfaceGLX {
  public:
   explicit PbufferGLSurfaceGLX(const gfx::Size& size);
 
   // Implement GLSurfaceGLX.
   virtual bool Initialize() OVERRIDE;
@@ skipping 11 matching lines @@
   gfx::Size size_;
   void* config_;
   XID pbuffer_;
 
   DISALLOW_COPY_AND_ASSIGN(PbufferGLSurfaceGLX);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_SURFACE_GLX_H_