Add metrics to keep track of the tab activate/deactivate cycle

chrome/browser/metrics/tab_usage_recorder.cc

Index: chrome/browser/metrics/tab_usage_recorder.cc
diff --git a/chrome/browser/metrics/tab_usage_recorder.cc b/chrome/browser/metrics/tab_usage_recorder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f52382c90517aada04301ce34f33bd7503f9aedb
--- /dev/null
+++ b/chrome/browser/metrics/tab_usage_recorder.cc
@@ -0,0 +1,136 @@
+// 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/tab_usage_recorder.h"
+
+#include "base/metrics/histogram_macros.h"
+#include "chrome/browser/bookmarks/bookmark_model_factory.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "components/bookmarks/browser/bookmark_model.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/web_contents_user_data.h"
+#include "content/public/common/page_importance_signals.h"
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(metrics::TabUsageRecorder::WebContentsData);
+
+namespace metrics {
+
+namespace {
+
+// This global is never freed.
+TabUsageRecorder* g_tab_usage_recorder = nullptr;
+
+}  // namespace
+
+// This class is responsible for recording the metrics. It also keeps track of
+// the pinned state of the tab.
+class TabUsageRecorder::WebContentsData
+    : public content::WebContentsUserData<WebContentsData> {
+ public:
+  ~WebContentsData() override;
+
+  void RecordTabDeactivation();
+  void RecordTabReactivation();
+
+  void OnTabPinnedStateChanging(bool is_pinned);
+
+ private:
+  friend class content::WebContentsUserData<WebContentsData>;
+
+  explicit WebContentsData(content::WebContents* contents);
+
+  // Returns true if |contents_|'s URL is bookmarked.
+  bool IsBookmarked();
+
+  // The WebContents associated to this instance.
+  content::WebContents* contents_;
+
+  // Indicates if the tab is pinned to the tab strip.
+  bool is_pinned_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebContentsData);
+};
+
+TabUsageRecorder::WebContentsData::~WebContentsData() = default;
+
+void TabUsageRecorder::WebContentsData::OnTabPinnedStateChanging(
+    bool is_pinned) {
+  is_pinned_ = is_pinned;
+}
+
+TabUsageRecorder::WebContentsData::WebContentsData(
+    content::WebContents* contents)
+    : contents_(contents), is_pinned_(false) {}
+
+bool TabUsageRecorder::WebContentsData::IsBookmarked() {
+  bookmarks::BookmarkModel* bookmark_model =
+      BookmarkModelFactory::GetForBrowserContextIfExists(
+          contents_->GetBrowserContext());
+
+  return bookmark_model &&
+         bookmark_model->IsBookmarked(contents_->GetLastCommittedURL());
+}
+
+void TabUsageRecorder::WebContentsData::RecordTabDeactivation() {
+  UMA_HISTOGRAM_BOOLEAN("Tab.Deactivation.Pinned", is_pinned_);
+  UMA_HISTOGRAM_BOOLEAN(
+      "Tab.Deactivation.HadFormInteraction",
+      contents_->GetPageImportanceSignals().had_form_interaction);
+  UMA_HISTOGRAM_BOOLEAN("Tab.Deactivation.Bookmarked", IsBookmarked());
+}
+
+void TabUsageRecorder::WebContentsData::RecordTabReactivation() {
+  UMA_HISTOGRAM_BOOLEAN("Tab.Reactivation.Pinned", is_pinned_);
+  UMA_HISTOGRAM_BOOLEAN(
+      "Tab.Reactivation.HadFormInteraction",
+      contents_->GetPageImportanceSignals().had_form_interaction);
+  UMA_HISTOGRAM_BOOLEAN("Tab.Reactivation.Bookmarked", IsBookmarked());
+}
+
+// static
+void TabUsageRecorder::Initialize() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!g_tab_usage_recorder);
+  g_tab_usage_recorder = new TabUsageRecorder();
+}
+
+void TabUsageRecorder::OnTabDeactivated(content::WebContents* contents) {
+  GetWebContentsData(contents)->RecordTabDeactivation();
+}
+
+void TabUsageRecorder::OnTabReactivated(content::WebContents* contents) {
+  GetWebContentsData(contents)->RecordTabReactivation();
+}
+
+void TabUsageRecorder::TabInsertedAt(TabStripModel* tab_strip_model,
+                                     content::WebContents* contents,
+                                     int index,
+                                     bool foreground) {
+  // Set the initial pinned value.
+  TabPinnedStateChanged(tab_strip_model, contents, index);
+}
+
+void TabUsageRecorder::TabPinnedStateChanged(TabStripModel* tab_strip_model,
+                                             content::WebContents* contents,
+                                             int index) {
+  GetWebContentsData(contents)->OnTabPinnedStateChanging(
+      tab_strip_model->IsTabPinned(index));
+}
+
+TabUsageRecorder::TabUsageRecorder()
+    : tab_reactivation_tracker_(this),
+      browser_tab_strip_tracker_(this, nullptr, nullptr) {
+  browser_tab_strip_tracker_.Init(
+      BrowserTabStripTracker::InitWith::ALL_BROWERS);
+}
+
+TabUsageRecorder::~TabUsageRecorder() = default;
+
+TabUsageRecorder::WebContentsData* TabUsageRecorder::GetWebContentsData(
+    content::WebContents* contents) {
+  WebContentsData::CreateForWebContents(contents);
+  return WebContentsData::FromWebContents(contents);
+}
+
+}  // namespace metrics