[webcrypto] Fix a race in BlinkPlatformImpl::crypto(), by using eager initilization of WebCryptoImpl

content/child/blink_platform_impl.h

 // 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.
 
 #ifndef CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_
 #define CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_
 
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
 #include "base/platform_file.h"
 #include "base/threading/thread_local_storage.h"
 #include "base/timer/timer.h"
+#include "content/child/webcrypto/webcrypto_impl.h"
 #include "content/child/webfallbackthemeengine_impl.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/Platform.h"
 #include "third_party/WebKit/public/platform/WebURLError.h"
 #include "ui/base/layout.h"
 
 #if defined(USE_DEFAULT_RENDER_THEME)
 #include "content/child/webthemeengine_impl_default.h"
 #elif defined(OS_WIN)
 #include "content/child/webthemeengine_impl_win.h"
@@ skipping 144 matching lines @@
   WebThemeEngineImpl native_theme_engine_;
   WebFallbackThemeEngineImpl fallback_theme_engine_;
   base::MessageLoop* main_loop_;
   base::OneShotTimer<BlinkPlatformImpl> shared_timer_;
   void (*shared_timer_func_)();
   double shared_timer_fire_time_;
   bool shared_timer_fire_time_was_set_while_suspended_;
   int shared_timer_suspended_;  // counter
   scoped_ptr<FlingCurveConfiguration> fling_curve_configuration_;
   base::ThreadLocalStorage::Slot current_thread_slot_;
-  scoped_ptr<WebCryptoImpl> web_crypto_;
+  WebCryptoImpl web_crypto_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_