Fix sky include guards to match Chromium style

sky/engine/core/dom/custom/CustomElementRegistrationContext.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef CustomElementRegistrationContext_h
-#define CustomElementRegistrationContext_h
+#ifndef SKY_ENGINE_CORE_DOM_CUSTOM_CUSTOMELEMENTREGISTRATIONCONTEXT_H_
+#define SKY_ENGINE_CORE_DOM_CUSTOM_CUSTOMELEMENTREGISTRATIONCONTEXT_H_
 
 #include "sky/engine/core/dom/QualifiedName.h"
 #include "sky/engine/core/dom/custom/CustomElementDescriptor.h"
 #include "sky/engine/core/dom/custom/CustomElementRegistry.h"
 #include "sky/engine/core/dom/custom/CustomElementUpgradeCandidateMap.h"
 #include "sky/engine/platform/heap/Handle.h"
 #include "sky/engine/wtf/HashMap.h"
 #include "sky/engine/wtf/PassOwnPtr.h"
 #include "sky/engine/wtf/PassRefPtr.h"
 #include "sky/engine/wtf/text/AtomicString.h"
@@ skipping 33 matching lines @@
     void resolveOrScheduleResolution(Element*, const AtomicString& typeExtension);
 
     CustomElementRegistry m_registry;
 
     // Element creation
     OwnPtr<CustomElementUpgradeCandidateMap> m_candidates;
 };
 
 }
 
-#endif // CustomElementRegistrationContext_h
+#endif  // SKY_ENGINE_CORE_DOM_CUSTOM_CUSTOMELEMENTREGISTRATIONCONTEXT_H_