Revert "[iOS] Fix Session.TotalDuration metric with multiwindow."

This reverts commit 8904382c.

Reason for revert: This CL breaks AppStateTest.resumeSessionWithStartupParameters for iOS 12 devices. See https://ci.chromium.org/ui/p/chrome/builders/ci/iphone-device/15349/blamelist.

Original change's description:
> [iOS] Fix Session.TotalDuration metric with multiwindow.
>
> Track the session as open while there is at least one foreground window.
> Log this in a dedicated app agent to avoid polluting AppState.
> The same is done to IOSProfileSessionDurationsService's session
> start/end events.
>
> Bug: 1156586
> Change-Id: I37586f989039206fbaa90f7ec4046fbf9582e70a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2599870
> Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
> Auto-Submit: Stepan Khapugin <stkhapugin@chromium.org>
> Reviewed-by: Mark Pearson <mpearson@chromium.org>
> Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
> Reviewed-by: Mark Cogan <marq@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#845653}

TBR=mpearson@chromium.org,marq@chromium.org,msarda@chromium.org,stkhapugin@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: Icd927a3252658933c02c8101067657f3ac7365b2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1156586
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2643264Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845730}

ios/chrome/app/BUILD.gn

@@ -148,20 +148,6 @@ source_set("content_suggestions_scheduler_app_state_agent") {
   ]
 }
 
-source_set("app_metrics_app_state_agent") {
-  configs += [ "//build/config/compiler:enable_arc" ]
-  sources = [
-    "app_metrics_app_state_agent.h",
-    "app_metrics_app_state_agent.mm",
-  ]
-  deps = [
-    "//base",
-    "//ios/chrome/app/application_delegate:app_state_header",
-    "//ios/chrome/browser/metrics",
-    "//ios/chrome/browser/ui/main:scene_state_header",
-  ]
-}
-
 source_set("app_internal") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
@@ -181,7 +167,6 @@ source_set("app_internal") {
 
   deps = [
     ":app",
-    ":app_metrics_app_state_agent",
     ":blocking_scene_commands",
     ":content_suggestions_scheduler_app_state_agent",
     ":mode",

ios/chrome/app/app_metrics_app_state_agent.h

-// Copyright 2020 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 IOS_CHROME_APP_APP_METRICS_APP_STATE_AGENT_H_
-#define IOS_CHROME_APP_APP_METRICS_APP_STATE_AGENT_H_
-
-#import <Foundation/Foundation.h>
-
-#import "ios/chrome/app/application_delegate/app_state_agent.h"
-
-// The agent that logs app-scoped metrics.
-@interface AppMetricsAppStateAgent : NSObject <AppStateAgent>
-@end
-
-#endif  // IOS_CHROME_APP_APP_METRICS_APP_STATE_AGENT_H_

ios/chrome/app/app_metrics_app_state_agent.mm

-// Copyright 2020 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.
-
-#import "ios/chrome/app/app_metrics_app_state_agent.h"
-
-#include "base/metrics/histogram_macros.h"
-#include "base/time/time.h"
-#import "ios/chrome/app/application_delegate/app_state.h"
-#import "ios/chrome/browser/metrics/ios_profile_session_durations_service.h"
-#import "ios/chrome/browser/metrics/ios_profile_session_durations_service_factory.h"
-#import "ios/chrome/browser/ui/main/scene_state.h"
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
-@interface AppMetricsAppStateAgent () <AppStateObserver, SceneStateObserver>
-
-// Observed app state.
-@property(nonatomic, weak) AppState* appState;
-
-@end
-
-@implementation AppMetricsAppStateAgent
-
-#pragma mark - AppStateAgent
-
-- (void)setAppState:(AppState*)appState {
-  // This should only be called once!
-  DCHECK(!_appState);
-
-  _appState = appState;
-  [appState addObserver:self];
-}
-
-#pragma mark - AppStateObserver
-
-- (void)appState:(AppState*)appState sceneConnected:(SceneState*)sceneState {
-  [sceneState addObserver:self];
-}
-
-- (void)appStateDidExitSafeMode:(AppState*)appState {
-  DCHECK(self.appState.lastTimeInForeground.is_null());
-  // Log session start. This normally happens in
-  // sceneState:transitionedToActivationLevel:, but is skipped in safe mode.
-  [self handleSessionStart];
-}
-
-#pragma mark - SceneStateObserver
-
-- (void)sceneState:(SceneState*)sceneState
-    transitionedToActivationLevel:(SceneActivationLevel)level {
-  if (self.appState.isInSafeMode) {
-    // Don't log any metrics at safe mode. Wait for AppStateObserver's
-    // -appStateDidExitSafeMode to log session start.
-    return;
-  }
-
-  if (level >= SceneActivationLevelForegroundInactive &&
-      self.appState.lastTimeInForeground.is_null()) {
-    [self handleSessionStart];
-  } else if (level <= SceneActivationLevelBackground) {
-    for (SceneState* scene in self.appState.connectedScenes) {
-      if (scene.activationLevel > SceneActivationLevelBackground) {
-        // One scene has gone background, but at least one other is still
-        // foreground. Consider the session ongoing.
-        return;
-      }
-    }
-
-    if (self.appState.lastTimeInForeground.is_null()) {
-      // This method will be called multiple times, once per scene, if multiple
-      // scenes go background simulatneously (for example, if two windows were
-      // in split screen and the user swiped to go home). Only log the session
-      // duration once.
-      return;
-    }
-
-    [self handleSessionEnd];
-    DCHECK(self.appState.lastTimeInForeground.is_null());
-  }
-}
-
-#pragma mark - private
-
-- (void)handleSessionStart {
-  self.appState.lastTimeInForeground = base::TimeTicks::Now();
-
-  IOSProfileSessionDurationsService* psdService = [self psdService];
-  if (psdService) {
-    psdService->OnSessionStarted(self.appState.lastTimeInForeground);
-  }
-}
-
-- (void)handleSessionEnd {
-  DCHECK(!self.appState.lastTimeInForeground.is_null());
-
-  base::TimeDelta duration =
-      base::TimeTicks::Now() - self.appState.lastTimeInForeground;
-
-  UMA_HISTOGRAM_LONG_TIMES("Session.TotalDuration", duration);
-  UMA_HISTOGRAM_CUSTOM_TIMES("Session.TotalDurationMax1Day", duration,
-                             base::TimeDelta::FromMilliseconds(1),
-                             base::TimeDelta::FromHours(24), 50);
-
-  IOSProfileSessionDurationsService* psdService = [self psdService];
-  if (psdService) {
-    psdService->OnSessionEnded(duration);
-  }
-
-  self.appState.lastTimeInForeground = base::TimeTicks();
-}
-
-- (IOSProfileSessionDurationsService*)psdService {
-  if (!self.appState.mainBrowserState) {
-    return nil;
-  }
-
-  return IOSProfileSessionDurationsServiceFactory::GetForBrowserState(
-      self.appState.mainBrowserState);
-}
-
-@end

ios/chrome/app/application_delegate/app_state.h

@@ -7,8 +7,6 @@
 
 #import <UIKit/UIKit.h>
 
-#include <memory>
-
 #import "ios/chrome/app/application_delegate/app_state_agent.h"
 #import "ios/chrome/browser/ui/main/scene_state_observer.h"
 #import "ios/chrome/browser/ui/scoped_ui_blocker/ui_blocker_manager.h"
@@ -26,10 +24,6 @@ class ChromeBrowserState;
 @protocol TabOpening;
 @protocol TabSwitching;
 
-namespace base {
-class TimeTicks;
-}
-
 @protocol AppStateObserver <NSObject>
 
 @optional
@@ -100,9 +94,6 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
 // multiple windows.
 @property(nonatomic, strong) NSString* previousSingleWindowSessionID;
 
-// Timestamp of when a scene was last becoming active. Can be null.
-@property(nonatomic, assign) base::TimeTicks lastTimeInForeground;
-
 // Saves the launchOptions to be used from -newTabFromLaunchOptions. If the
 // application is in background, initialize the browser to basic. If not, launch
 // the browser.

ios/chrome/app/application_delegate/app_state.mm

@@ -38,6 +38,8 @@
 #include "ios/chrome/browser/feature_engagement/tracker_factory.h"
 #import "ios/chrome/browser/geolocation/omnibox_geolocation_config.h"
 #import "ios/chrome/browser/main/browser.h"
+#import "ios/chrome/browser/metrics/ios_profile_session_durations_service.h"
+#import "ios/chrome/browser/metrics/ios_profile_session_durations_service_factory.h"
 #import "ios/chrome/browser/signin/authentication_service.h"
 #import "ios/chrome/browser/signin/authentication_service_factory.h"
 #import "ios/chrome/browser/ui/authentication/signed_in_accounts_view_controller.h"
@@ -98,6 +100,8 @@ const NSTimeInterval kMemoryFootprintRecordingTimeInterval = 5;
   // Variables backing properties of same name.
   SafeModeCoordinator* _safeModeCoordinator;
 
+  // Start of the current session, used for UMA.
+  base::TimeTicks _sessionStartTime;
   // YES if the app is currently in the process of terminating.
   BOOL _appIsTerminating;
   // Whether the application is currently in the background.
@@ -383,6 +387,8 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
   DCHECK([_browserLauncher browserInitializationStage] ==
          INITIALIZATION_STAGE_FOREGROUND);
 
+  _sessionStartTime = base::TimeTicks::Now();
+
   id<BrowserInterface> currentInterface =
       _browserLauncher.interfaceProvider.currentInterface;
   CommandDispatcher* dispatcher =
@@ -409,6 +415,12 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
     [HandlerForProtocol(dispatcher, HelpCommands) showHelpBubbleIfEligible];
   }
 
+  IOSProfileSessionDurationsService* psdService =
+      IOSProfileSessionDurationsServiceFactory::GetForBrowserState(
+          currentInterface.browserState);
+  if (psdService)
+    psdService->OnSessionStarted(_sessionStartTime);
+
   [MetricsMediator logStartupDuration:self.startupInformation
                 connectionInformation:connectionInformation];
 }
@@ -495,6 +507,11 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
 
   id<BrowserInterface> currentInterface =
       _browserLauncher.interfaceProvider.currentInterface;
+  base::TimeDelta duration = base::TimeTicks::Now() - _sessionStartTime;
+  UMA_HISTOGRAM_LONG_TIMES("Session.TotalDuration", duration);
+  UMA_HISTOGRAM_CUSTOM_TIMES("Session.TotalDurationMax1Day", duration,
+                             base::TimeDelta::FromMilliseconds(1),
+                             base::TimeDelta::FromHours(24), 50);
 
   // Record session metrics (currentInterface.browserState may be null during
   // tests).
@@ -516,6 +533,14 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
           ->RecordAndClearSessionMetrics(MetricsToRecordFlags::kNoMetrics);
     }
   }
+
+  if (currentInterface.browserState) {
+    IOSProfileSessionDurationsService* psdService =
+        IOSProfileSessionDurationsServiceFactory::GetForBrowserState(
+            currentInterface.browserState);
+    if (psdService)
+      psdService->OnSessionEnded(duration);
+  }
 }
 
 - (BOOL)requiresHandlingAfterLaunchWithOptions:(NSDictionary*)launchOptions

ios/chrome/app/main_controller.mm

@@ -26,7 +26,6 @@
 #import "components/previous_session_info/previous_session_info.h"
 #include "components/ukm/ios/features.h"
 #include "components/web_resource/web_resource_pref_names.h"
-#include "ios/chrome/app/app_metrics_app_state_agent.h"
 #import "ios/chrome/app/application_delegate/metrics_mediator.h"
 #import "ios/chrome/app/blocking_scene_commands.h"
 #import "ios/chrome/app/content_suggestions_scheduler_app_state_agent.h"
@@ -605,7 +604,6 @@ void MainControllerAuthenticationServiceDelegate::ClearBrowsingData(
   [appState addObserver:self];
 
   // Create app state agents.
-  [appState addAgent:[[AppMetricsAppStateAgent alloc] init]];
   [appState addAgent:[[ContentSuggestionsSchedulerAppAgent alloc] init]];
   [appState addAgent:[[IncognitoUsageAppStateAgent alloc] init]];
 

tools/metrics/histograms/histograms_xml/session/histograms.xml

@@ -135,16 +135,26 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
     when Chrome leaves the screen. This is generally straightforward. Chrome
     leaves the screen when the screen goes blank or shows the lock screen, when
     Chrome clicks a link that opens in another app, or when the user switches to
-    another app in the app switcher. Note that, unlike on desktop, even if
-    Chrome is playing media in the background or in picture-in-picture mode, the
-    session is still terminated when Chrome leaves the screen. Also note that if
-    Chrome starts in Safe Mode, the session will only start when the user quits
-    Safe Mode. When multiple windows are used, the session is considered ongoing
-    as long as there is at least one foreground Chrome window. This was revised
-    in M-89 to support multiple windows. In M-87 and M-88, nothing was logged
-    due to a bug. Before M-86, a similar metric was recorded, with some
-    differences in edge cases. See the old histogram description for more
-    details.
+    the app switcher. Note that, unlike on desktop, even if Chrome is playing
+    media in the background, the session is still terminated when Chrome leaves
+    the screen.
+
+    iOS continued: These are some edge cases to be aware of: (i) OS overlays.
+    These can appear, for examples, when a link is clicked that could go to a
+    non-Google app that has not yet been set to default and the OS asks whether
+    to open the link in the app by default, or when a user has set the OS to
+    block certain sites or types of sites by default and require authentication
+    to access them. This authentication prompt is an OS overlay. At the time of
+    writing this description, we're not sure if displaying an overlay will end
+    the session. (ii) full-screen media playing. Because media is played through
+    iOS's technology stack, if the user takes media that's playing within Chrome
+    and displayed it full-screen, the session ends because no part of Chrome is
+    on the screen anymore. (iii) multi-window support. Not yet launched as of
+    M-85. Sessions end and immediately restart when a user switches from a
+    single-window to a multi-window view and vice versa, and also ends when
+    resizing the Chrome window. The end is because Chrome is considered no
+    longer active during the time the OS animates the windows to change their
+    sizes.
 
     This histogram is of special interest to the chrome-analysis-team@. Do not
     change its semantics or retire it without talking to them first.