Various cleaups for AMP page load metrics.

chrome/browser/page_load_metrics/page_load_metrics_util.h

Index: chrome/browser/page_load_metrics/page_load_metrics_util.h
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_util.h b/chrome/browser/page_load_metrics/page_load_metrics_util.h
index a0af192a8b21db5b51127f0313538d4dab7576b6..1e6af5716c95d5d73e6b3f7ac37c3955a13d8c08 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_util.h
+++ b/chrome/browser/page_load_metrics/page_load_metrics_util.h
@@ -131,6 +131,21 @@ bool DidObserveLoadingBehaviorInAnyFrame(
     const page_load_metrics::PageLoadExtraInfo& info,
     blink::WebLoadingBehaviorFlag behavior);
 
+// Whether the given url has a google hostname.
+bool IsGoogleHostname(const GURL& url);
+
+// If the given hostname is a google hostname, returns the portion of the
+// hostname before the google hostname. Otherwise, returns an unset optional
+// value.
+//
+// For example:
+//   https://example.com/foo => returns an unset optional value
+//   https://google.com/foo => returns ''
+//   https://www.google.com/foo => returns 'www'
+//   https://news.google.com/foo => returns 'news'
+//   https://a.b.c.google.com/foo => returns 'a.b.c'
+base::Optional<std::string> GetGoogleHostnamePrefix(const GURL& url);
+
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_UTIL_H_