Implement StringUTF8Adaptor::asStringPiece.

third_party/WebKit/Source/wtf/text/StringUTF8Adaptor.h

Index: third_party/WebKit/Source/wtf/text/StringUTF8Adaptor.h
diff --git a/third_party/WebKit/Source/wtf/text/StringUTF8Adaptor.h b/third_party/WebKit/Source/wtf/text/StringUTF8Adaptor.h
index 567bb995d67b9eda9f0bc6849e168c447299dfba..10928b3c1af3bcc37e713ae2c9c0a1784c072177 100644
--- a/third_party/WebKit/Source/wtf/text/StringUTF8Adaptor.h
+++ b/third_party/WebKit/Source/wtf/text/StringUTF8Adaptor.h
@@ -31,6 +31,7 @@
 #ifndef StringUTF8Adaptor_h
 #define StringUTF8Adaptor_h
 
+#include "base/strings/string_piece.h"
 #include "wtf/text/CString.h"
 #include "wtf/text/TextEncoding.h"
 #include "wtf/text/WTFString.h"
@@ -65,6 +66,8 @@ public:
     const char* data() const { return m_data; }
     size_t length() const { return m_length; }
 
+    base::StringPiece asStringPiece() const { return base::StringPiece(m_data, m_length); }
+
 private:
     CString m_utf8Buffer;
     const char* m_data;