Rename DesktopEngagement* to DesktopSessionDuration*.

chrome/browser/metrics/desktop_session/desktop_session_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_METRICS_DESKTOP_ENGAGEMENT_DESKTOP_ENGAGEMENT_OBSERVER_H_
-#define CHROME_BROWSER_METRICS_DESKTOP_ENGAGEMENT_DESKTOP_ENGAGEMENT_OBSERVER_H_
+#ifndef CHROME_BROWSER_METRICS_DESKTOP_SESSION_DESKTOP_SESSION_OBSERVER_H_
+#define CHROME_BROWSER_METRICS_DESKTOP_SESSION_DESKTOP_SESSION_OBSERVER_H_
 
 #include "base/macros.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 
 namespace metrics {
 
-class DesktopEngagementService;
+class DesktopSessionService;
 
 // Tracks user input events from web contents and notifies
-// |DesktopEngagementService|.
-class DesktopEngagementObserver
+// |DesktopSessionService|.
+class DesktopSessionObserver
     : public content::WebContentsObserver,
-      public content::WebContentsUserData<DesktopEngagementObserver>,
+      public content::WebContentsUserData<DesktopSessionObserver>,
       public content::RenderWidgetHost::InputEventObserver {
  public:
-  DesktopEngagementObserver(content::WebContents* web_contents,
-                            DesktopEngagementService* service);
-  ~DesktopEngagementObserver() override;
+  DesktopSessionObserver(content::WebContents* web_contents,
+                         DesktopSessionService* service);
+  ~DesktopSessionObserver() override;
 
-  static DesktopEngagementObserver* CreateForWebContents(
+  static DesktopSessionObserver* CreateForWebContents(
       content::WebContents* web_contents);
 
  private:
-  friend class content::WebContentsUserData<DesktopEngagementObserver>;
+  friend class content::WebContentsUserData<DesktopSessionObserver>;
 
   // Register / Unregister input event callback to given RenderViewHost
   void RegisterInputEventObserver(content::RenderViewHost* host);
   void UnregisterInputEventObserver(content::RenderViewHost* host);
 
   // content::RenderWidgetHost::InputEventObserver:
   void OnInputEvent(const blink::WebInputEvent& event) override;
 
   // content::WebContentsObserver:
   void RenderViewHostChanged(content::RenderViewHost* old_host,
                              content::RenderViewHost* new_host) override;
 
-  DesktopEngagementService* service_;
+  DesktopSessionService* service_;
 
-  DISALLOW_COPY_AND_ASSIGN(DesktopEngagementObserver);
+  DISALLOW_COPY_AND_ASSIGN(DesktopSessionObserver);
 };
 
 }  // namespace metrics
 
-#endif  // CHROME_BROWSER_METRICS_DESKTOP_ENGAGEMENT_DESKTOP_ENGAGEMENT_OBSERVER_H_
+#endif  // CHROME_BROWSER_METRICS_DESKTOP_SESSION_DESKTOP_SESSION_OBSERVER_H_