Create an interface that TabStatsDataStore conforms to.

This is the first step needed to enable defining a similar class that
will detect different chromium usage scenarios to be recorded alongside
power use.

Bug: 1153193
Change-Id: I29e59a8cffae7cc5962882f78c8fbbf29073a170
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2597013
Commit-Queue: Oliver Li <olivierli@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844802}

chrome/browser/BUILD.gn

@@ -3740,6 +3740,7 @@ static_library("browser") {
       "metrics/incognito_observer_desktop.cc",
       "metrics/tab_stats_data_store.cc",
       "metrics/tab_stats_data_store.h",
+      "metrics/tab_stats_handler.h",
       "metrics/tab_stats_tracker.cc",
       "metrics/tab_stats_tracker.h",
       "metrics/tab_stats_tracker_delegate.h",

chrome/browser/metrics/tab_stats_data_store.cc

@@ -102,6 +102,24 @@ void TabStatsDataStore::OnTabReplaced(content::WebContents* old_contents,
   existing_tabs_[new_contents] = old_contents_id;
 }
 
+void TabStatsDataStore::OnTabInteraction(content::WebContents* web_contents) {
+  DCHECK(base::Contains(existing_tabs_, web_contents));
+  TabID web_contents_id = GetTabID(web_contents);
+  // Mark the tab as interacted with in all the intervals.
+  for (auto& interval_map : interval_maps_) {
+    DCHECK(base::Contains(*interval_map, web_contents_id));
+    (*interval_map)[web_contents_id].interacted_during_interval = true;
+  }
+}
+
+void TabStatsDataStore::OnTabAudible(content::WebContents* web_contents) {
+  OnTabAudibleOrVisible(web_contents);
+}
+
+void TabStatsDataStore::OnTabVisible(content::WebContents* web_contents) {
+  OnTabAudibleOrVisible(web_contents);
+}
+
 void TabStatsDataStore::UpdateMaxTabsPerWindowIfNeeded(size_t value) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   if (value <= tab_stats_.max_tab_per_window)
@@ -129,24 +147,6 @@ void TabStatsDataStore::ResetMaximumsToCurrentState() {
   }
 }
 
-void TabStatsDataStore::OnTabInteraction(content::WebContents* web_contents) {
-  DCHECK(base::Contains(existing_tabs_, web_contents));
-  TabID web_contents_id = GetTabID(web_contents);
-  // Mark the tab as interacted with in all the intervals.
-  for (auto& interval_map : interval_maps_) {
-    DCHECK(base::Contains(*interval_map, web_contents_id));
-    (*interval_map)[web_contents_id].interacted_during_interval = true;
-  }
-}
-
-void TabStatsDataStore::OnTabAudible(content::WebContents* web_contents) {
-  OnTabAudibleOrVisible(web_contents);
-}
-
-void TabStatsDataStore::OnTabVisible(content::WebContents* web_contents) {
-  OnTabAudibleOrVisible(web_contents);
-}
-
 TabStatsDataStore::TabsStateDuringIntervalMap*
 TabStatsDataStore::AddInterval() {
   // Creates the interval and initialize its data.

chrome/browser/metrics/tab_stats_data_store.h

@@ -12,6 +12,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/optional.h"
 #include "base/sequence_checker.h"
+#include "chrome/browser/metrics/tab_stats_handler.h"
 #include "chrome/browser/resource_coordinator/lifecycle_unit_state.mojom.h"
 
 using mojom::LifecycleUnitDiscardReason;
@@ -27,9 +28,9 @@ namespace metrics {
 FORWARD_DECLARE_TEST(TabStatsTrackerBrowserTest,
                      TabDeletionGetsHandledProperly);
 
-// The data store that keeps track of all the information that the
-// TabStatsTracker wants to track.
-class TabStatsDataStore {
+// Keeps track of all the information needed by TabStatsTracker. Stats are
+// stored internally to be retrieved at a later point.
+class TabStatsDataStore : public TabStatsHandler {
  public:
   // Houses all of the statistics gathered by the TabStatsTracker.
   struct TabsStats {
@@ -82,14 +83,16 @@ class TabStatsDataStore {
   explicit TabStatsDataStore(PrefService* pref_service);
   virtual ~TabStatsDataStore();
 
-  // Functions used to update the window/tab count.
-  void OnWindowAdded();
-  void OnWindowRemoved();
-  // Virtual for unittesting.
-  virtual void OnTabAdded(content::WebContents* web_contents);
-  virtual void OnTabRemoved(content::WebContents* web_contents);
+  // TabStatsHandler:
+  void OnWindowAdded() override;
+  void OnWindowRemoved() override;
+  void OnTabAdded(content::WebContents* web_contents) override;
+  void OnTabRemoved(content::WebContents* web_contents) override;
   void OnTabReplaced(content::WebContents* old_contents,
-                     content::WebContents* new_contents);
+                     content::WebContents* new_contents) override;
+  void OnTabInteraction(content::WebContents* web_contents) override;
+  void OnTabAudible(content::WebContents* web_contents) override;
+  void OnTabVisible(content::WebContents* web_contents) override;
 
   // Update the maximum number of tabs in a single window if |value| exceeds
   // this.
@@ -101,18 +104,6 @@ class TabStatsDataStore {
   // metrics have been reported.
   void ResetMaximumsToCurrentState();
 
-  // Records that there's been a direct user interaction with a tab, see the
-  // comment for |DidGetUserInteraction| in
-  // content/public/browser/web_contents_observer.h for a list of the possible
-  // type of interactions.
-  void OnTabInteraction(content::WebContents* web_contents);
-
-  // Records that a tab became audible.
-  void OnTabAudible(content::WebContents* web_contents);
-
-  // Records that a tab became visible.
-  void OnTabVisible(content::WebContents* web_contents);
-
   // Creates a new interval map. The returned pointer is owned by |this|.
   TabsStateDuringIntervalMap* AddInterval();
 
@@ -120,9 +111,7 @@ class TabStatsDataStore {
   void ResetIntervalData(TabsStateDuringIntervalMap* interval_map);
 
   const TabsStats& tab_stats() const { return tab_stats_; }
-
   base::Optional<TabID> GetTabIDForTesting(content::WebContents* web_contents);
-
   base::flat_map<content::WebContents*, TabID>* existing_tabs_for_testing() {
     return &existing_tabs_;
   }

chrome/browser/metrics/tab_stats_handler.h

+// Copyright 2021 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_TAB_STATS_HANDLER_H_
+#define CHROME_BROWSER_METRICS_TAB_STATS_HANDLER_H_
+
+namespace content {
+class WebContents;
+}  // namespace content
+
+namespace metrics {
+
+// Defines an interface for a class used to handle tab and window related stats.
+// Handling the events can be either storing them for logging purposes,
+// forwarding them to another class or taking reactive measures when certain
+// criteria are met.
+class TabStatsHandler {
+ public:
+  // Functions used to update the window/tab count.
+  virtual void OnWindowAdded() = 0;
+  virtual void OnWindowRemoved() = 0;
+  virtual void OnTabAdded(content::WebContents* web_contents) = 0;
+  virtual void OnTabRemoved(content::WebContents* web_contents) = 0;
+  virtual void OnTabReplaced(content::WebContents* old_contents,
+                             content::WebContents* new_contents) = 0;
+
+  // Records that there's been a direct user interaction with a tab, see the
+  // comment for |DidGetUserInteraction| in
+  // content/public/browser/web_contents_observer.h for a list of the possible
+  // type of interactions.
+  virtual void OnTabInteraction(content::WebContents* web_contents) = 0;
+
+  // Records that a tab became audible.
+  virtual void OnTabAudible(content::WebContents* web_contents) = 0;
+
+  // Records that a tab became visible.
+  virtual void OnTabVisible(content::WebContents* web_contents) = 0;
+};
+
+}  // namespace metrics
+
+#endif  // CHROME_BROWSER_METRICS_TAB_STATS_HANDLER_H_