Fix sky include guards to match Chromium style

sky/engine/core/html/parser/HTMLSrcsetParser.h

 /*
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 11 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 HTMLSrcsetParser_h
-#define HTMLSrcsetParser_h
+#ifndef SKY_ENGINE_CORE_HTML_PARSER_HTMLSRCSETPARSER_H_
+#define SKY_ENGINE_CORE_HTML_PARSER_HTMLSRCSETPARSER_H_
 
 #include "sky/engine/wtf/text/WTFString.h"
 
 namespace blink {
 
 enum { UninitializedDescriptor = -1 };
 
 class DescriptorParsingResult {
 public:
     DescriptorParsingResult()
@@ skipping 86 matching lines @@
 };
 
 ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, unsigned sourceSize, const String& srcsetAttribute);
 
 ImageCandidate bestFitSourceForImageAttributes(float deviceScaleFactor, unsigned sourceSize, const String& srcAttribute, const String& srcsetAttribute);
 
 String bestFitSourceForImageAttributes(float deviceScaleFactor, unsigned sourceSize, const String& srcAttribute, ImageCandidate& srcsetImageCandidate);
 
 }
 
-#endif
+#endif  // SKY_ENGINE_CORE_HTML_PARSER_HTMLSRCSETPARSER_H_