Update {virtual,override} to follow C++11 style in ppapi.

ppapi/shared_impl/media_stream_buffer_manager_unittest.cc

 // Copyright 2014 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 "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/shared_impl/media_stream_buffer_manager.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 12 matching lines @@
   return shared_memory.Pass();
 }
 
 }  // namespace
 
 namespace ppapi {
 
 class MockDelegate : public MediaStreamBufferManager::Delegate {
  public:
   MockDelegate() : new_buffer_enqueue_counter_(0) {}
-  virtual void OnNewBufferEnqueued() override {
+  void OnNewBufferEnqueued() override {
     new_buffer_enqueue_counter_++;
   }
 
   int32_t new_buffer_enqueue_counter_;
 };
 
 TEST(MediaStreamBufferManager, General) {
   {
     const int32_t kNumberOfBuffers = 5;
     const int32_t kBufferSize = 128;
@@ skipping 132 matching lines @@
     // Test DequeueBuffer() and GetBufferPointer()
     for (int32_t i = 0; i < kNumberOfBuffers2; ++i) {
       EXPECT_EQ(i, manager.DequeueBuffer());
       EXPECT_EQ(reinterpret_cast<MediaStreamBuffer*>(memory + i * kBufferSize2),
                 manager.GetBufferPointer(i));
     }
   }
 }
 
 }  // namespace ppapi