Use explicit WebString <-> string16 conversion methods in storage API files

third_party/WebKit/public/platform/WebString.h

 /*
  * Copyright (C) 2009 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 54 matching lines @@
 // * webstring.utf8()
 // * webstring.utf16()
 // * WebString::toNullableString16(webstring)
 //
 // Some types like GURL and base::FilePath can directly take either utf-8 or
 // utf-16 strings. Use following methods to convert WebString to/from GURL or
 // FilePath rather than going through intermediate string types:
 //
 // * GURL WebStringToGURL(const WebString&)
 // * base::FilePath WebStringToFilePath(const WebString&)
+// * WebString FilePathToWebString(const base::FilePath&);
 //
 // It is inexpensive to copy a WebString object.
 // WARNING: It is not safe to pass a WebString across threads!!!
 //
 class WebString {
  public:
   ~WebString() { reset(); }
 
   WebString() {}
 
@@ skipping 146 matching lines @@
   return a.equals(b);
 }
 
 inline bool operator!=(const WebString& a, const WebString& b) {
   return !(a == b);
 }
 
 }  // namespace blink
 
 #endif