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

chrome/browser/page_load_metrics/observers/ads_detection.cc

Index: chrome/browser/page_load_metrics/observers/ads_detection.cc
diff --git a/chrome/browser/page_load_metrics/observers/ads_detection.cc b/chrome/browser/page_load_metrics/observers/ads_detection.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7d16d492e22e46fe27c224a5b37e1c9ff4520988
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/ads_detection.cc
@@ -0,0 +1,30 @@
+// 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.
+
+#include "chrome/browser/page_load_metrics/observers/ads_detection.h"
+
+#include "base/strings/string_util.h"
+#include "url/gurl.h"
+
+bool IsAdFrame(base::StringPiece frame_name, const GURL& frame_url) {
+  // Google ads are prevalent and easy to track, so we'll start by tracking
+  // those. Note that the frame name can be very large, so be careful to avoid
+  // full string searches if possible.
+  // TODO(jkarlin): Track other ad networks that are easy to identify.
+
+  if (base::StartsWith(frame_name, "google_ads_iframe",
+                       base::CompareCase::SENSITIVE) ||
+      base::StartsWith(frame_name, "google_ads_frame",
+                       base::CompareCase::SENSITIVE)) {
+    return true;
+  }
+
+  if (frame_url.host_piece() == "tpc.googlesyndication.com" &&
+      base::StartsWith(frame_url.path_piece(), "/safeframe",
+                       base::CompareCase::SENSITIVE)) {
+    return true;
+  }
+
+  return false;
+}