Make ExtensionIconSet::ContainsPath use StringPiece.

extensions/browser/url_request_util.cc

Index: extensions/browser/url_request_util.cc
diff --git a/extensions/browser/url_request_util.cc b/extensions/browser/url_request_util.cc
index 28d863389078857b11a65b32410543a20e7d433a..c7347cdbe956a4fc74d847daccf7175c1b3885d2 100644
--- a/extensions/browser/url_request_util.cc
+++ b/extensions/browser/url_request_util.cc
@@ -67,9 +67,10 @@ bool AllowCrossRendererResourceLoad(net::URLRequest* request,
   // hybrid hosted/packaged apps. The one exception is access to icons, since
   // some extensions want to be able to do things like create their own
   // launchers.
-  std::string resource_root_relative_path =
-      request->url().path().empty() ? std::string()
-                                    : request->url().path().substr(1);
+  base::StringPiece resource_root_relative_path =
+      request->url().path_piece().empty()
+          ? base::StringPiece()
+          : request->url().path_piece().substr(1);
   if (extension->is_hosted_app() &&
       !IconsInfo::GetIcons(extension)
            .ContainsPath(resource_root_relative_path)) {