Refactor client visibility handling

gpu/command_buffer/client/context_support.h

Index: gpu/command_buffer/client/context_support.h
diff --git a/gpu/command_buffer/client/context_support.h b/gpu/command_buffer/client/context_support.h
index 99e94045326adf8b4abcd2acd1570f085789ee9d..c72cf37f16f20ab805672197f7e1ad2200a06036 100644
--- a/gpu/command_buffer/client/context_support.h
+++ b/gpu/command_buffer/client/context_support.h
@@ -56,10 +56,6 @@ class ContextSupport {
   virtual void SetErrorMessageCallback(
       const base::Callback<void(const char*, int32_t)>& callback) = 0;
 
-  // Called when a client of the context has changed visibility.
-  virtual void SetClientVisible(int client_id, bool is_visible) = 0;
-  virtual bool AnyClientsVisible() const = 0;
-
  protected:
   ContextSupport() {}
   virtual ~ContextSupport() {}