Standardize usage of virtual/override/final in content/

content/common/gpu/gpu_channel_manager.cc

Index: content/common/gpu/gpu_channel_manager.cc
diff --git a/content/common/gpu/gpu_channel_manager.cc b/content/common/gpu/gpu_channel_manager.cc
index 9a8a0f4f8f08976b70d0e80b356fa08a34abde1e..fd9e5f8f40cd09eda2d3352d53f5a1ee616861f7 100644
--- a/content/common/gpu/gpu_channel_manager.cc
+++ b/content/common/gpu/gpu_channel_manager.cc
@@ -31,17 +31,17 @@ class GpuChannelManagerMessageFilter : public IPC::MessageFilter {
       GpuMemoryBufferFactory* gpu_memory_buffer_factory)
       : sender_(NULL), gpu_memory_buffer_factory_(gpu_memory_buffer_factory) {}
 
-  virtual void OnFilterAdded(IPC::Sender* sender) override {
+  void OnFilterAdded(IPC::Sender* sender) override {
     DCHECK(!sender_);
     sender_ = sender;
   }
 
-  virtual void OnFilterRemoved() override {
+  void OnFilterRemoved() override {
     DCHECK(sender_);
     sender_ = NULL;
   }
 
-  virtual bool OnMessageReceived(const IPC::Message& message) override {
+  bool OnMessageReceived(const IPC::Message& message) override {
     DCHECK(sender_);
     bool handled = true;
     IPC_BEGIN_MESSAGE_MAP(GpuChannelManagerMessageFilter, message)
@@ -52,7 +52,7 @@ class GpuChannelManagerMessageFilter : public IPC::MessageFilter {
   }
 
  protected:
-  virtual ~GpuChannelManagerMessageFilter() {}
+  ~GpuChannelManagerMessageFilter() override {}
 
   void OnCreateGpuMemoryBuffer(const gfx::GpuMemoryBufferHandle& handle,
                                const gfx::Size& size,