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

extensions/browser/extension_protocols.cc

Index: extensions/browser/extension_protocols.cc
diff --git a/extensions/browser/extension_protocols.cc b/extensions/browser/extension_protocols.cc
index c231083a1b2533c7e094c3d88a128a4ff3f8db8d..3bdbc18927532b962916a42eba2ba3e1b14a83d3 100644
--- a/extensions/browser/extension_protocols.cc
+++ b/extensions/browser/extension_protocols.cc
@@ -392,7 +392,7 @@ bool URLIsForExtensionIcon(const GURL& url, const Extension* extension) {
   if (!extension)
     return false;
 
-  std::string path = url.path();
+  std::string path = url.path().as_string();
   DCHECK_EQ(url.host(), extension->id());
   DCHECK(path.length() > 0 && path[0] == '/');
   path = path.substr(1);
@@ -454,7 +454,7 @@ ExtensionProtocolHandler::MaybeCreateJob(
   bool follow_symlinks_anywhere = false;
 
   if (extension) {
-    std::string resource_path = request->url().path();
+    std::string resource_path = request->url().path().as_string();
 
     // Use default CSP for <webview>.
     if (!url_request_util::IsWebViewRequest(request)) {
@@ -477,7 +477,7 @@ ExtensionProtocolHandler::MaybeCreateJob(
   }
 
   // Create a job for a generated background page.
-  std::string path = request->url().path();
+  std::string path = request->url().path().as_string();
   if (path.size() > 1 &&
       path.substr(1) == extensions::kGeneratedBackgroundPageFilename) {
     return new GeneratedBackgroundPageJob(