Use FrameIsAd to decide whether to isolate a frame in TopDocumentIsolation mode.

chrome/browser/page_load_metrics/observers/ads_detection.h

Index: chrome/browser/page_load_metrics/observers/ads_detection.h
diff --git a/chrome/browser/page_load_metrics/observers/ads_detection.h b/chrome/browser/page_load_metrics/observers/ads_detection.h
new file mode 100644
index 0000000000000000000000000000000000000000..538236bebd66999560cbcfde67fb8efe8298ea06
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/ads_detection.h
@@ -0,0 +1,17 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_ADS_DETECTION_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_ADS_DETECTION_H_
+
+#include <string>
+
+#include "base/strings/string_piece_forward.h"
+
+class GURL;
+
+// Uses various heuristics to determine if a given frame hosts an advertisment.
+bool IsAdFrame(base::StringPiece frame_name, const GURL& frame_url);
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_ADS_DETECTION_H_