Add common page filtering logic for page load metrics.

chrome/common/page_load_metrics/page_track_decider.h

Index: chrome/common/page_load_metrics/page_track_decider.h
diff --git a/chrome/common/page_load_metrics/page_track_decider.h b/chrome/common/page_load_metrics/page_track_decider.h
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+++ b/chrome/common/page_load_metrics/page_track_decider.h
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+// Copyright 2016 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_COMMON_PAGE_LOAD_METRICS_PAGE_TRACK_DECIDER_H_
+#define CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_TRACK_DECIDER_H_
+
+#include "base/macros.h"
+
+namespace page_load_metrics {
+
+// PageTrackDecider is an interface used to determine whether metrics should be
+// tracked for a given page. This class is used by the core page load metrics
+// tracking infrastructure in both the browser and render processes so policy
+// decisions about which page loads to track are consistent across processes.
+class PageTrackDecider {
+ public:
+  PageTrackDecider();
+  virtual ~PageTrackDecider();
+
+  // Whether metrics should be tracked for the current page. This method invokes
+  // the pure virtual methods below to decide whether metrics should be tracked.
+  bool ShouldTrack();
+
+  // Whether the navigation for the current page has committed.
+  virtual bool HasCommitted() = 0;
+
+  // Whether the current page's URL is HTTP or HTTPS. Note that the page does
+  // not need to have committed, nor does the URL or hostname of the URL need to
+  // point at a valid web page or host, for this method to return true.
+  virtual bool IsHttpOrHttpsUrl() = 0;
+
+  // Whether the current page's URL is for a Chrome new tab page. Note that in
+  // some cases the new tab page is served over the network via https.
+  virtual bool IsNewTabPageUrl() = 0;
+
+  // The methods below can only be called if HasCommitted() returns true.
+
+  // Whether the current page is a Chrome-generated error page. Example error
+  // pages include pages displayed after a network error that did not result in
+  // receiving an HTTP/HTTPS response, such as the 'There is no Internet
+  // connection' page, which is displayed when the user attempts to navigate
+  // without an Internet connection. This method returns false for non-Chrome
+  // generated error pages, such as pages with 4xx/5xx response codes. To
+  // check whether the current page resulted in a 4xx/5xx error, use
+  // IsHTTPErrorPage() instead.
+  virtual bool IsChromeErrorPage() = 0;
+
+  // Returns the HTTP status code for the current page, or -1 if no status code
+  // is available.
+  virtual int GetHttpStatusCode() = 0;
+
+  // Whether the current page is an HTML or XHTML page.
+  virtual bool IsHtmlOrXhtmlPage() = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PageTrackDecider);
+};
+
+}  // namespace page_load_metrics
+
+#endif  // CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_TRACK_DECIDER_H_