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

extensions/shell/browser/shell_nacl_browser_delegate.cc

Index: extensions/shell/browser/shell_nacl_browser_delegate.cc
diff --git a/extensions/shell/browser/shell_nacl_browser_delegate.cc b/extensions/shell/browser/shell_nacl_browser_delegate.cc
index 88db0fd7407b8dd638c9b75cdb581372d3811723..e4c38896084a4b8d65a5942f74e682b6dae2b4d4 100644
--- a/extensions/shell/browser/shell_nacl_browser_delegate.cc
+++ b/extensions/shell/browser/shell_nacl_browser_delegate.cc
@@ -159,7 +159,7 @@ bool ShellNaClBrowserDelegate::MapUrlToLocalFilePath(
   // handles a subset of the urls.
   if (!use_blocking_api) {
     if (file_url.SchemeIs(kExtensionScheme)) {
-      std::string path = file_url.path();
+      std::string path = file_url.path().as_string();
       base::TrimString(path, "/", &path);  // Remove first slash
       *file_path = extension->path().AppendASCII(path);
       return true;
@@ -169,7 +169,8 @@ bool ShellNaClBrowserDelegate::MapUrlToLocalFilePath(
 
   // Check that the URL references a resource in the extension.
   // NOTE: app_shell does not support shared modules.
-  ExtensionResource resource = extension->GetResource(file_url.path());
+  ExtensionResource resource =
+      extension->GetResource(file_url.path().as_string());
   if (resource.empty())
     return false;