Standardize usage of virtual/override/final specifiers.

content/common/gpu/gpu_memory_buffer_factory_x11.cc

Index: content/common/gpu/gpu_memory_buffer_factory_x11.cc
diff --git a/content/common/gpu/gpu_memory_buffer_factory_x11.cc b/content/common/gpu/gpu_memory_buffer_factory_x11.cc
index 0f713923c0cd5a24b81437d7239a781a2576481e..bb9ef567020544b61f493f32f19bb516580424ab 100644
--- a/content/common/gpu/gpu_memory_buffer_factory_x11.cc
+++ b/content/common/gpu/gpu_memory_buffer_factory_x11.cc
@@ -17,7 +17,7 @@ class GpuMemoryBufferFactoryImpl : public GpuMemoryBufferFactory,
                                    public gpu::ImageFactory {
  public:
   // Overridden from GpuMemoryBufferFactory:
-  virtual gfx::GpuMemoryBufferHandle CreateGpuMemoryBuffer(
+  gfx::GpuMemoryBufferHandle CreateGpuMemoryBuffer(
       const gfx::GpuMemoryBufferHandle& handle,
       const gfx::Size& size,
       gfx::GpuMemoryBuffer::Format format,
@@ -32,7 +32,7 @@ class GpuMemoryBufferFactoryImpl : public GpuMemoryBufferFactory,
         return gfx::GpuMemoryBufferHandle();
     }
   }
-  virtual void DestroyGpuMemoryBuffer(
+  void DestroyGpuMemoryBuffer(
       const gfx::GpuMemoryBufferHandle& handle) override {
     switch (handle.type) {
       case gfx::X11_PIXMAP_BUFFER:
@@ -43,10 +43,10 @@ class GpuMemoryBufferFactoryImpl : public GpuMemoryBufferFactory,
         break;
     }
   }
-  virtual gpu::ImageFactory* AsImageFactory() override { return this; }
+  gpu::ImageFactory* AsImageFactory() override { return this; }
 
   // Overridden from gpu::GpuMemoryBufferFactory:
-  virtual scoped_refptr<gfx::GLImage> CreateImageForGpuMemoryBuffer(
+  scoped_refptr<gfx::GLImage> CreateImageForGpuMemoryBuffer(
       const gfx::GpuMemoryBufferHandle& handle,
       const gfx::Size& size,
       gfx::GpuMemoryBuffer::Format format,