Instrumenting copying string returned by GetRawDataResource to locate the source of jankiness.

Previous instrumentations showed that the jank is in this line:
*data = rb.GetRawDataResource(resource_id_).as_string();
And its average run time is 15.1 ms.
I also know that the expensive operation is outside of ResourceBundle::GetRawDataResourceForScale.
So, we have to suggest that it's indeed copying the string that is responsible for the jank.

BUG=422489

Review URL: https://codereview.chromium.org/702543005

Cr-Commit-Position: refs/heads/master@{#302686}

chrome/browser/extensions/chrome_url_request_util.cc

@@ -75,7 +75,15 @@ class URLRequestResourceBundleJob : public net::URLRequestSimpleJob {
         FROM_HERE_WITH_EXPLICIT_FUNCTION(
             "422489 URLRequestResourceBundleJob::GetData 1"));
 
-    *data = rb.GetRawDataResource(resource_id_).as_string();
+    const base::StringPiece resource_as_string_piece =
+        rb.GetRawDataResource(resource_id_);
+
+    // TODO(vadimt): Remove ScopedTracker below once crbug.com/422489 is fixed.
+    tracked_objects::ScopedTracker tracking_profile15(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "422489 URLRequestResourceBundleJob::GetData 1.5"));
+
+    *data = resource_as_string_piece.as_string();
 
     // TODO(vadimt): Remove ScopedTracker below once crbug.com/422489 is fixed.
     tracked_objects::ScopedTracker tracking_profile2(