Rename DesktopEngagement* to DesktopSessionDuration*.

chrome/browser/metrics/desktop_engagement/audible_contents_tracker.cc

-// 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.
-
-#include "chrome/browser/metrics/desktop_engagement/audible_contents_tracker.h"
-
-#include "chrome/browser/metrics/desktop_engagement/desktop_engagement_service.h"
-#include "chrome/browser/ui/browser.h"
-#include "chrome/browser/ui/browser_list.h"
-#include "chrome/browser/ui/tabs/tab_strip_model.h"
-
-namespace metrics {
-
-AudibleContentsTracker::AudibleContentsTracker(Observer* observer)
-    : observer_(observer) {
-  BrowserList* browser_list = BrowserList::GetInstance();
-  for (Browser* browser : *browser_list)
-    browser->tab_strip_model()->AddObserver(this);
-  browser_list->AddObserver(this);
-}
-
-AudibleContentsTracker::~AudibleContentsTracker() {
-  BrowserList::GetInstance()->RemoveObserver(this);
-}
-
-void AudibleContentsTracker::OnBrowserAdded(Browser* browser) {
-  browser->tab_strip_model()->AddObserver(this);
-}
-
-void AudibleContentsTracker::OnBrowserRemoved(Browser* browser) {
-  browser->tab_strip_model()->RemoveObserver(this);
-}
-
-void AudibleContentsTracker::TabClosingAt(TabStripModel* model,
-                                          content::WebContents* web_contents,
-                                          int index) {
-  RemoveAudibleWebContents(web_contents);
-}
-
-void AudibleContentsTracker::TabChangedAt(content::WebContents* web_contents,
-                                          int index,
-                                          TabChangeType change_type) {
-  // Ignore 'loading' and 'title' changes.
-  if (change_type != TabStripModelObserver::ALL)
-    return;
-
-  if (web_contents->WasRecentlyAudible())
-    AddAudibleWebContents(web_contents);
-  else
-    RemoveAudibleWebContents(web_contents);
-}
-
-void AudibleContentsTracker::TabReplacedAt(
-    TabStripModel* model,
-    content::WebContents* old_web_contents,
-    content::WebContents* new_web_contents,
-    int index) {
-  RemoveAudibleWebContents(old_web_contents);
-  if (new_web_contents->WasRecentlyAudible())
-    AddAudibleWebContents(new_web_contents);
-}
-
-void AudibleContentsTracker::AddAudibleWebContents(
-    content::WebContents* web_contents) {
-  // The first web contents to become audible indicates that audio has started.
-  bool added = audible_contents_.insert(web_contents).second;
-  if (added && audible_contents_.size() == 1)
-    observer_->OnAudioStart();
-}
-
-void AudibleContentsTracker::RemoveAudibleWebContents(
-    content::WebContents* web_contents) {
-  // If the web content was previously audible and there are no other audible
-  // web contents then notify that audio ended.
-  bool removed = (audible_contents_.erase(web_contents) == 1);
-  if (removed && audible_contents_.empty())
-    observer_->OnAudioEnd();
-}
-
-}  // namespace metrics