Framework to ascribe all network data use to a source.

chrome/browser/data_use_measurement/data_use_web_contents_observer.h

+// 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_BROWSER_DATA_USE_MEASUREMENT_DATA_USE_WEB_CONTENTS_OBSERVER_H_
+#define CHROME_BROWSER_DATA_USE_MEASUREMENT_DATA_USE_WEB_CONTENTS_OBSERVER_H_
+
+#include "base/macros.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_user_data.h"
+
+namespace content {
+class NavigationHandle;
+class RenderFrameHost;
+}
+
+namespace data_use_measurement {
+
+class ChromeDataUseAscriberService;
+
+// Forwards navigation and frame events to |ChromeDataUseAscriberService|.
+class DataUseWebContentsObserver
+    : public content::WebContentsObserver,
+      public content::WebContentsUserData<DataUseWebContentsObserver> {
+ public:
+  // Creates a |DataUseWebContentsObserver| for the given |WebContents| and
+  // |ChromeDataUseAscriberService|.
+  static void CreateForWebContents(content::WebContents* web_contents,
+                                   ChromeDataUseAscriberService* service);
+
+  ~DataUseWebContentsObserver() override;
+
+  // Called when a render frame host is created. Propagates this event to

[Lei Zhang, 2016/09/08 22:04:43]

Just write a class summary to explain this class forwards events. Group all the
overrides together.

[Not at Google. Contact bengr, 2016/09/09 18:37:16]

Done.

+  // |ChromeDataUseAscriberService|.
+  void RenderFrameCreated(content::RenderFrameHost* render_frame_host) override;
+
+  // Called when a render frame host is deleted. Propagates this event to
+  // |ChromeDataUseAscriberService|.
+  void RenderFrameDeleted(content::RenderFrameHost* render_frame_host) override;
+
+  // Called when a navigation is started. Propagates this event to
+  // |ChromeDataUseAscriberService|.
+  void DidStartNavigation(
+      content::NavigationHandle* navigation_handle) override;
+
+  // Called when a navigation is completed. Propagates this event to
+  // |ChromeDataUseAscriberService|.
+  void DidFinishNavigation(
+      content::NavigationHandle* navigation_handle) override;
+
+  // Called when a navigation is redirected. Propagates this event to
+  // |ChromeDataUseAscriberService|.
+  void DidRedirectNavigation(
+      content::NavigationHandle* navigation_handle) override;
+
+ private:
+  explicit DataUseWebContentsObserver(content::WebContents* web_contents,

[Lei Zhang, 2016/09/08 22:04:43]

Multiple parameters - not explicit.

[Not at Google. Contact bengr, 2016/09/09 18:37:17]

Done.

+                                      ChromeDataUseAscriberService* service);
+  friend class content::WebContentsUserData<DataUseWebContentsObserver>;

[Lei Zhang, 2016/09/08 22:04:43]

Put the friend first and add a blank line before the member variables.

[Not at Google. Contact bengr, 2016/09/09 18:37:16]

Done.

+  ChromeDataUseAscriberService* service_;

[Lei Zhang, 2016/09/08 22:04:43]

ChromeDataUseAscriberService* const service_;

[Not at Google. Contact bengr, 2016/09/09 18:37:17]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(DataUseWebContentsObserver);
+};
+
+}  // namespace data_use_measurement
+
+#endif  // CHROME_BROWSER_DATA_USE_MEASUREMENT_DATA_USE_WEB_CONTENTS_OBSERVER_H_