[WIP] make GURL::path() return a StringPiece

net/cookies/canonical_cookie.cc

Index: net/cookies/canonical_cookie.cc
diff --git a/net/cookies/canonical_cookie.cc b/net/cookies/canonical_cookie.cc
index de2fbbe6c65f03826722b05646936e95ad0ae536..649937ce1b8163a9191c71408cc9b82dcd41604e 100644
--- a/net/cookies/canonical_cookie.cc
+++ b/net/cookies/canonical_cookie.cc
@@ -92,7 +92,7 @@ std::string CanonPathWithString(const GURL& url,
   //    Set-Cookie response, up to, but not including, the
   //    right-most /."""
   // How would this work for a cookie on /?  We will include it then.
-  const std::string& url_path = url.path();
+  base::StringPiece url_path = url.path();
 
   size_t idx = url_path.find_last_of('/');
 
@@ -101,7 +101,7 @@ std::string CanonPathWithString(const GURL& url,
     return std::string("/");
 
   // Return up to the rightmost '/'.
-  return url_path.substr(0, idx);
+  return url_path.as_string().substr(0, idx);
 }
 
 // Compares cookies using name, domain and path, so that "equivalent" cookies
@@ -310,8 +310,7 @@ bool CanonicalCookie::IsEquivalentForSecureCookieMatching(
           ecc.IsOnPath(Path()));
 }
 
-bool CanonicalCookie::IsOnPath(const std::string& url_path) const {
-
+bool CanonicalCookie::IsOnPath(const base::StringPiece& url_path) const {
   // A zero length would be unsafe for our trailing '/' checks, and
   // would also make no sense for our prefix match.  The code that
   // creates a CanonicalCookie should make sure the path is never zero length,