[ios] Adds engagement metrics recording to the Feed

- DiscoverFeedService is now in charge of creating and owning a single
instance of FeedMetricsRecorder.
- Add the FeedMetricsRecorder to DiscoverFeedConfig
- Adds engagement recording events

Bug: 1085419, 1127557
Change-Id: Iaf3cdcca850babb54bc8149050a4ebd6c3f8d68c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2406715
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Ganggui Tang <gogerald@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806747}

ios/chrome/browser/discover_feed/BUILD.gn

@@ -18,6 +18,7 @@ source_set("discover_feed") {
     "//components/signin/public/identity_manager",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/signin",
+    "//ios/chrome/browser/ui/content_suggestions:metrics",
     "//ios/public/provider/chrome/browser",
     "//ios/public/provider/chrome/browser/discover_feed",
   ]

ios/chrome/browser/discover_feed/discover_feed_service.h

@@ -9,6 +9,7 @@
 #include "components/signin/public/identity_manager/identity_manager.h"
 
 class ChromeBrowserState;
+@class DiscoverFeedMetricsRecorder;
 class DiscoverFeedProvider;
 
 // A browser-context keyed service that is used to keep the Discover Feed data
@@ -20,6 +21,10 @@ class DiscoverFeedService : public KeyedService,
   DiscoverFeedService(ChromeBrowserState* browser_state);
   ~DiscoverFeedService() override;
 
+  // Returns the FeedMetricsRecorder to be used by the Feed, a single instance
+  // of DiscoverFeedMetricsRecorder needs to be used per BrowserState.
+  DiscoverFeedMetricsRecorder* GetDiscoverFeedMetricsRecorder();
+
   // KeyedService:
   void Shutdown() override;
 
@@ -36,6 +41,9 @@ class DiscoverFeedService : public KeyedService,
   // Discover Feed provider to notify of changes.
   DiscoverFeedProvider* discover_feed_provider_;
 
+  // Metrics recorder for the DiscoverFeed.
+  DiscoverFeedMetricsRecorder* discover_feed_metrics_recorder_;
+
   DISALLOW_COPY_AND_ASSIGN(DiscoverFeedService);
 };
 

ios/chrome/browser/discover_feed/discover_feed_service.mm

@@ -7,6 +7,7 @@
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #import "ios/chrome/browser/signin/authentication_service_factory.h"
 #include "ios/chrome/browser/signin/identity_manager_factory.h"
+#import "ios/chrome/browser/ui/content_suggestions/discover_feed_metrics_recorder.h"
 #import "ios/public/provider/chrome/browser/chrome_browser_provider.h"
 #import "ios/public/provider/chrome/browser/discover_feed/discover_feed_configuration.h"
 #import "ios/public/provider/chrome/browser/discover_feed/discover_feed_provider.h"
@@ -23,14 +24,22 @@ DiscoverFeedService::DiscoverFeedService(ChromeBrowserState* browser_state) {
     identity_manager_->AddObserver(this);
   }
 
+  discover_feed_metrics_recorder_ = [[DiscoverFeedMetricsRecorder alloc] init];
+
   DiscoverFeedConfiguration* discover_config =
       [[DiscoverFeedConfiguration alloc] init];
   discover_config.browserState = browser_state;
+  discover_config.metricsRecorder = discover_feed_metrics_recorder_;
   discover_feed_provider_->StartFeed(discover_config);
 }
 
 DiscoverFeedService::~DiscoverFeedService() {}
 
+DiscoverFeedMetricsRecorder*
+DiscoverFeedService::GetDiscoverFeedMetricsRecorder() {
+  return discover_feed_metrics_recorder_;
+}
+
 void DiscoverFeedService::Shutdown() {
   if (identity_manager_) {
     identity_manager_->RemoveObserver(this);

ios/chrome/browser/ui/content_suggestions/BUILD.gn

@@ -23,8 +23,6 @@ source_set("content_suggestions") {
     "content_suggestions_service_bridge_observer.h",
     "content_suggestions_service_bridge_observer.mm",
     "discover_feed_delegate.h",
-    "discover_feed_metrics_recorder.h",
-    "discover_feed_metrics_recorder.mm",
     "mediator_util.h",
     "mediator_util.mm",
     "ntp_home_mediator.h",
@@ -35,6 +33,7 @@ source_set("content_suggestions") {
   ]
   deps = [
     ":feature_flags",
+    ":metrics",
     "//base",
     "//components/favicon/core",
     "//components/feature_engagement/public",
@@ -103,6 +102,7 @@ source_set("content_suggestions") {
     "//ui/base",
     "//ui/strings",
   ]
+  public_deps = [ ":metrics" ]
   configs += [ "//build/config/compiler:enable_arc" ]
 }
 
@@ -151,6 +151,7 @@ source_set("content_suggestions_ui") {
     ":content_suggestions_constant",
     ":content_suggestions_ui_util",
     ":feature_flags",
+    ":metrics",
     "resources:content_suggestions_no_image",
     "resources:content_suggestions_offline",
     "resources:ntp_search_icon",
@@ -185,6 +186,15 @@ source_set("content_suggestions_ui") {
   configs += [ "//build/config/compiler:enable_arc" ]
 }
 
+source_set("metrics") {
+  sources = [
+    "discover_feed_metrics_recorder.h",
+    "discover_feed_metrics_recorder.mm",
+  ]
+  deps = [ "//base" ]
+  configs += [ "//build/config/compiler:enable_arc" ]
+}
+
 source_set("content_suggestions_constant") {
   sources = [
     "ntp_home_constant.h",

ios/chrome/browser/ui/content_suggestions/content_suggestions_coordinator.mm

@@ -19,6 +19,7 @@
 #import "components/search_engines/template_url.h"
 #import "components/search_engines/template_url_service.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#include "ios/chrome/browser/discover_feed/discover_feed_service.h"
 #include "ios/chrome/browser/discover_feed/discover_feed_service_factory.h"
 #include "ios/chrome/browser/drag_and_drop/drag_and_drop_flag.h"
 #import "ios/chrome/browser/drag_and_drop/url_drag_drop_handler.h"
@@ -209,8 +210,11 @@
 
   if (IsDiscoverFeedEnabled()) {
     // Creating the DiscoverFeedService will start the DiscoverFeed.
-    DiscoverFeedServiceFactory::GetForBrowserState(
-        self.browser->GetBrowserState());
+    DiscoverFeedService* discoverFeedService =
+        DiscoverFeedServiceFactory::GetForBrowserState(
+            self.browser->GetBrowserState());
+    self.discoverFeedMetricsRecorder =
+        discoverFeedService->GetDiscoverFeedMetricsRecorder();
   }
   self.discoverFeedViewController = [self discoverFeed];
 
@@ -239,7 +243,6 @@
   self.metricsRecorder = [[ContentSuggestionsMetricsRecorder alloc] init];
   self.metricsRecorder.delegate = self.contentSuggestionsMediator;
 
-  self.discoverFeedMetricsRecorder = [[DiscoverFeedMetricsRecorder alloc] init];
 
   // Offset to maintain Discover feed scroll position.
   CGFloat offset = 0;
@@ -266,6 +269,8 @@
       self.browser->GetCommandDispatcher(), SnackbarCommands);
   self.suggestionsViewController.dispatcher = dispatcher;
   self.suggestionsViewController.discoverFeedMenuHandler = self;
+  self.suggestionsViewController.discoverFeedMetricsRecorder =
+      self.discoverFeedMetricsRecorder;
 
   self.discoverFeedHeaderDelegate =
       self.suggestionsViewController.discoverFeedHeaderDelegate;

ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.h

@@ -21,6 +21,7 @@
 @protocol ContentSuggestionsViewControllerAudience;
 @protocol DiscoverFeedHeaderChanging;
 @protocol DiscoverFeedMenuCommands;
+@class DiscoverFeedMetricsRecorder;
 @protocol OverscrollActionsControllerDelegate;
 @protocol SnackbarCommands;
 @protocol SuggestedContent;
@@ -69,6 +70,9 @@ extern NSString* const
 // Provider of menu configurations for the contentSuggestions component.
 @property(nonatomic, weak) id<ContentSuggestionsMenuProvider> menuProvider
     API_AVAILABLE(ios(13.0));
+// Discover Feed metrics recorder.
+@property(nonatomic, strong)
+    DiscoverFeedMetricsRecorder* discoverFeedMetricsRecorder;
 
 - (void)setDataSource:(id<ContentSuggestionsDataSource>)dataSource;
 - (void)setDispatcher:(id<SnackbarCommands>)dispatcher;

ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.mm

@@ -28,6 +28,7 @@
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_metrics_recording.h"
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller_audience.h"
 #import "ios/chrome/browser/ui/content_suggestions/discover_feed_menu_commands.h"
+#import "ios/chrome/browser/ui/content_suggestions/discover_feed_metrics_recorder.h"
 #import "ios/chrome/browser/ui/content_suggestions/ntp_home_constant.h"
 #import "ios/chrome/browser/ui/content_suggestions/theme_change_delegate.h"
 #import "ios/chrome/browser/ui/ntp/new_tab_page_header_constants.h"
@@ -90,6 +91,9 @@ NSString* const kContentSuggestionsMostVisitedAccessibilityIdentifierPrefix =
 // Whether this VC is observing the discoverFeedHeight using KVO or not.
 @property(nonatomic, assign) BOOL observingDiscoverFeedHeight;
 
+// The CollectionViewController scroll position when an scrolling event starts.
+@property(nonatomic, assign) int scrollStartPosition;
+
 @end
 
 @implementation ContentSuggestionsViewController
@@ -742,6 +746,7 @@ NSString* const kContentSuggestionsMostVisitedAccessibilityIdentifierPrefix =
 
 - (void)scrollViewWillBeginDragging:(UIScrollView*)scrollView {
   [self.overscrollActionsController scrollViewWillBeginDragging:scrollView];
+  self.scrollStartPosition = scrollView.contentOffset.y;
 }
 
 - (void)scrollViewDidEndDragging:(UIScrollView*)scrollView
@@ -749,6 +754,8 @@ NSString* const kContentSuggestionsMostVisitedAccessibilityIdentifierPrefix =
   [super scrollViewDidEndDragging:scrollView willDecelerate:decelerate];
   [self.overscrollActionsController scrollViewDidEndDragging:scrollView
                                               willDecelerate:decelerate];
+  [self.discoverFeedMetricsRecorder
+      recordFeedScrolled:scrollView.contentOffset.y - self.scrollStartPosition];
 }
 
 - (void)scrollViewWillEndDragging:(UIScrollView*)scrollView

ios/chrome/browser/ui/content_suggestions/discover_feed_metrics_recorder.h

@@ -10,6 +10,9 @@
 // Records different metrics for the NTP's Discover feed.
 @interface DiscoverFeedMetricsRecorder : NSObject
 
+// Record metrics for when the user has scrolled |scrollDistance| in the Feed.
+- (void)recordFeedScrolled:(int)scrollDistance;
+
 // Record metrics for when the user has reached the bottom of their current
 // feed.
 - (void)recordInfiniteFeedTriggered;

ios/chrome/browser/ui/content_suggestions/discover_feed_metrics_recorder.mm

@@ -4,6 +4,7 @@
 
 #import "ios/chrome/browser/ui/content_suggestions/discover_feed_metrics_recorder.h"
 
+#import "base/mac/foundation_util.h"
 #import "base/metrics/histogram_macros.h"
 #import "base/metrics/user_metrics.h"
 #import "base/metrics/user_metrics_action.h"
@@ -78,6 +79,19 @@ enum class FeedUserActionType {
   kMaxValue = kAddedToReadLater,
 };
 
+// Values for the UMA ContentSuggestions.Feed.EngagementType
+// histogram. These values are persisted to logs. Entries should not be
+// renumbered and numeric values should never be reused. This must be kept
+// in sync with FeedEngagementType in enums.xml.
+enum class FeedEngagementType {
+  kFeedEngaged = 0,
+  kFeedEngagedSimple = 1,
+  kFeedInteracted = 2,
+  kDeprecatedFeedScrolled = 3,
+  kFeedScrolled = 4,
+  kMaxValue = kFeedScrolled,
+};
+
 namespace {
 // Histogram name for the infinite feed trigger.
 const char kDiscoverFeedInfiniteFeedTriggered[] =
@@ -116,12 +130,48 @@ const char kDiscoverFeedUserActionManageInterestsTapped[] =
 // User action name for infinite feed triggering.
 const char kDiscoverFeedUserActionInfiniteFeedTriggered[] =
     "ContentSuggestions.Feed.InfiniteFeedTriggered";
+
+// Histogram name for the feed engagement types.
+const char kDiscoverFeedEngagementTypeHistogram[] =
+    "ContentSuggestions.Feed.EngagementType";
+
+// Minimum scrolling amount to record a FeedEngagementType::kFeedEngaged due to
+// scrolling.
+const int kMinScrollThreshold = 160;
+
+// Time between two metrics recorded to consider it a new session.
+const int kMinutesBetweenSessions = 5;
 }  // namespace
 
+@interface DiscoverFeedMetricsRecorder ()
+
+// Tracking property to avoid duplicate recordings of
+// FeedEngagementType::kFeedEngagedSimple.
+@property(nonatomic, assign) BOOL engagedSimpleReported;
+// Tracking property to avoid duplicate recordings of
+// FeedEngagementType::kFeedEngaged.
+@property(nonatomic, assign) BOOL engagedReported;
+// Tracking property to avoid duplicate recordings of
+// FeedEngagementType::kFeedScrolled.
+@property(nonatomic, assign) BOOL scrolledReported;
+// The time when the first metric is being recorded for this session.
+@property(nonatomic, assign) base::Time sessionStartTime;
+
+@end
+
 @implementation DiscoverFeedMetricsRecorder
 
 #pragma mark - Public
 
+- (void)recordFeedScrolled:(int)scrollDistance {
+  [self recordEngagement:scrollDistance interacted:NO];
+
+  if (!self.scrolledReported) {
+    [self recordEngagementTypeHistogram:FeedEngagementType::kFeedScrolled];
+    self.scrolledReported = YES;
+  }
+}
+
 - (void)recordInfiniteFeedTriggered {
   UMA_HISTOGRAM_ENUMERATION(kDiscoverFeedInfiniteFeedTriggered,
                             FeedLoadStreamStatus::kLoadedFromNetwork);
@@ -202,6 +252,61 @@ const char kDiscoverFeedUserActionInfiniteFeedTriggered[] =
 // Records histogram metrics for Discover feed user actions.
 - (void)recordDiscoverFeedUserActionHistogram:(FeedUserActionType)actionType {
   UMA_HISTOGRAM_ENUMERATION(kDiscoverFeedUserActionHistogram, actionType);
+  [self recordInteraction];
+}
+
+// Records Feed engagement.
+- (void)recordEngagement:(int)scrollDistance interacted:(BOOL)interacted {
+  scrollDistance = abs(scrollDistance);
+
+  // Determine if this interaction is part of a new 'session'.
+  base::Time now = base::Time::Now();
+  base::TimeDelta visitTimeout =
+      base::TimeDelta::FromMinutes(kMinutesBetweenSessions);
+  if (now - self.sessionStartTime > visitTimeout) {
+    [self finalizeSession];
+  }
+  // Reset the last active time for session measurement.
+  self.sessionStartTime = now;
+
+  // Report the user as engaged-simple if they have scrolled any amount or
+  // interacted with the card, and we have not already reported it for this
+  // chrome run.
+  if (!self.engagedSimpleReported && (scrollDistance > 0 || interacted)) {
+    [self recordEngagementTypeHistogram:FeedEngagementType::kFeedEngagedSimple];
+    self.engagedSimpleReported = YES;
+  }
+
+  // Report the user as engaged if they have scrolled more than the threshold or
+  // interacted with the card, and we have not already reported it this chrome
+  // run.
+  if (!self.engagedReported &&
+      (scrollDistance > kMinScrollThreshold || interacted)) {
+    [self recordEngagementTypeHistogram:FeedEngagementType::kFeedEngaged];
+    self.engagedReported = YES;
+  }
+}
+
+// Records any direct interaction with the Feed, this doesn't include scrolling.
+- (void)recordInteraction {
+  [self recordEngagement:0 interacted:YES];
+  [self recordEngagementTypeHistogram:FeedEngagementType::kFeedInteracted];
+}
+
+// Records Engagement histograms of |engagementType|.
+- (void)recordEngagementTypeHistogram:(FeedEngagementType)engagementType {
+  UMA_HISTOGRAM_ENUMERATION(kDiscoverFeedEngagementTypeHistogram,
+                            engagementType);
+}
+
+// Resets the session tracking values, this occurs if there's been
+// kMinutesBetweenSessions minutes between sessions.
+- (void)finalizeSession {
+  if (!self.engagedSimpleReported)
+    return;
+  self.engagedReported = NO;
+  self.engagedSimpleReported = NO;
+  self.scrolledReported = NO;
 }
 
 @end

ios/public/provider/chrome/browser/discover_feed/discover_feed_configuration.h

@@ -8,6 +8,7 @@
 #import <Foundation/Foundation.h>
 
 class ChromeBrowserState;
+@class DiscoverFeedMetricsRecorder;
 
 // Configuration object used by the DiscoverFeedProvider.
 @interface DiscoverFeedConfiguration : NSObject
@@ -15,6 +16,9 @@ class ChromeBrowserState;
 // BrowserState used by DiscoverFeedProvider;
 @property(nonatomic, assign) ChromeBrowserState* browserState;
 
+// DiscoverFeed metrics recorder used by DiscoverFeedProvider;
+@property(nonatomic, strong) DiscoverFeedMetricsRecorder* metricsRecorder;
+
 @end
 
 #endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_DISCOVER_FEED_DISCOVER_FEED_CONFIGURATION_H_