Add input event counts to tab activity UKMs

This adds counters for key, mouse, and touch events to
TabActivityWatcher::WebContentsData. When a tab is logged, these
counters are reported in the UKM. The counters are reset on each
navigation.

These counters are passed to TabSnapshotLogger in a new hierarchical
structure, which will be built upon to add browser-, tab- and page-
specific metrics. Separating these event counts into a separate struct
makes it easier to reset them when a navigation occurs.

This CL counts the absolute number of events -- as an improvement, we
would prefer to count user actions rather than, say, the exact
number of mouse-move events fired.

A unit test simulates mouse activity, but key and touch are harder to
pipe in from a unit test.

Bug: 784639
Change-Id: I693c34f0845c3fdeca6c1fb172e7347f9c2a504f
Reviewed-on: https://chromium-review.googlesource.com/794592
Commit-Queue: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520674}

chrome/browser/ui/tabs/tab_activity_watcher.cc

@@ -13,10 +13,13 @@
 #include "chrome/common/chrome_features.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "services/metrics/public/cpp/ukm_source_id.h"
+#include "third_party/WebKit/public/platform/WebInputEvent.h"
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(TabActivityWatcher::WebContentsData);
 
@@ -37,7 +40,8 @@ constexpr char kPerSourceLogTimeoutMsecParamName[] =
 // per-WebContents data that TabActivityWatcher uses to log the tab.
 class TabActivityWatcher::WebContentsData
     : public content::WebContentsObserver,
-      public content::WebContentsUserData<WebContentsData> {
+      public content::WebContentsUserData<WebContentsData>,
+      public content::RenderWidgetHost::InputEventObserver {
  public:
   ~WebContentsData() override = default;
 
@@ -48,6 +52,10 @@ class TabActivityWatcher::WebContentsData
 
   ukm::SourceId ukm_source_id() const { return ukm_source_id_; }
 
+  const TabMetricsLogger::TabMetrics& tab_metrics() const {
+    return tab_metrics_;
+  }
+
   base::TimeTicks last_log_time_for_source() const {
     return last_log_time_for_source_;
   }
@@ -56,9 +64,18 @@ class TabActivityWatcher::WebContentsData
   friend class content::WebContentsUserData<WebContentsData>;
 
   explicit WebContentsData(content::WebContents* web_contents)
-      : WebContentsObserver(web_contents) {}
+      : WebContentsObserver(web_contents) {
+    tab_metrics_.web_contents = web_contents;
+    web_contents->GetRenderViewHost()->GetWidget()->AddInputEventObserver(this);
+  }
 
   // content::WebContentsObserver:
+  void RenderViewHostChanged(content::RenderViewHost* old_host,
+                             content::RenderViewHost* new_host) override {
+    if (old_host != nullptr)
+      old_host->GetWidget()->RemoveInputEventObserver(this);
+    new_host->GetWidget()->AddInputEventObserver(this);
+  }
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override {
     if (!navigation_handle->HasCommitted() ||
@@ -77,17 +94,33 @@ class TabActivityWatcher::WebContentsData
 
     // Clear the per-SourceId last log time.
     last_log_time_for_source_ = base::TimeTicks();
+
+    // Reset the per-page data.
+    tab_metrics_.page_metrics = {};
   }
   void WasHidden() override {
     TabActivityWatcher::GetInstance()->OnWasHidden(web_contents());
   }
 
+  // content::RenderWidgetHost::InputEventObserver:
+  void OnInputEvent(const blink::WebInputEvent& event) override {
+    if (blink::WebInputEvent::IsMouseEventType(event.GetType()))
+      tab_metrics_.page_metrics.mouse_event_count++;
+    else if (blink::WebInputEvent::IsKeyboardEventType(event.GetType()))
+      tab_metrics_.page_metrics.key_event_count++;
+    else if (blink::WebInputEvent::IsTouchEventType(event.GetType()))
+      tab_metrics_.page_metrics.touch_event_count++;
+  }
+
   // Updated when a navigation is finished.
   ukm::SourceId ukm_source_id_ = 0;
 
   // Used to throttle event logging per SourceId.
   base::TimeTicks last_log_time_for_source_;
 
+  // Stores current stats for the tab.
+  TabMetricsLogger::TabMetrics tab_metrics_;
+
   DISALLOW_COPY_AND_ASSIGN(WebContentsData);
 };
 
@@ -146,7 +179,8 @@ void TabActivityWatcher::MaybeLogTab(content::WebContents* web_contents) {
   }
 
   ukm::SourceId ukm_source_id = web_contents_data->ukm_source_id();
-  tab_metrics_logger_->LogBackgroundTab(ukm_source_id, web_contents);
+  tab_metrics_logger_->LogBackgroundTab(ukm_source_id,
+                                        web_contents_data->tab_metrics());
   web_contents_data->DidLog(now);
 }
 

chrome/browser/ui/tabs/tab_metrics_logger.h

@@ -16,12 +16,32 @@ class WebContents;
 // Must be used on the UI thread.
 class TabMetricsLogger {
  public:
+  // The state of the page loaded in a tab's main frame, starting since the last
+  // navigation.
+  struct PageMetrics {
+    // Number of key events.
+    int key_event_count = 0;
+    // Number of mouse events.
+    int mouse_event_count = 0;
+    // Number of touch events.
+    int touch_event_count = 0;
+  };
+
+  // The state of a tab.
+  struct TabMetrics {
+    content::WebContents* web_contents = nullptr;
+
+    // Per-page metrics of the state of the WebContents. Tracked since the
+    // tab's last top-level navigation.
+    PageMetrics page_metrics = {};
+  };
+
   virtual ~TabMetricsLogger() = default;
 
   // Logs metrics for the tab with the given main frame WebContents. Does
   // nothing if |ukm_source_id| is zero.
   virtual void LogBackgroundTab(ukm::SourceId ukm_source_id,
-                                content::WebContents* web_contents) = 0;
+                                const TabMetrics& tab_metrics) = 0;
 };
 
 #endif  // CHROME_BROWSER_UI_TABS_TAB_METRICS_LOGGER_H_

chrome/browser/ui/tabs/tab_metrics_logger_impl.cc

@@ -64,9 +64,8 @@ int GetSiteEngagementScore(const content::WebContents* web_contents) {
 TabMetricsLoggerImpl::TabMetricsLoggerImpl() = default;
 TabMetricsLoggerImpl::~TabMetricsLoggerImpl() = default;
 
-void TabMetricsLoggerImpl::LogBackgroundTab(
-    ukm::SourceId ukm_source_id,
-    content::WebContents* web_contents) {
+void TabMetricsLoggerImpl::LogBackgroundTab(ukm::SourceId ukm_source_id,
+                                            const TabMetrics& tab_metrics) {
   if (!ukm_source_id)
     return;
 
@@ -74,6 +73,7 @@ void TabMetricsLoggerImpl::LogBackgroundTab(
   if (!ukm_recorder)
     return;
 
+  content::WebContents* web_contents = tab_metrics.web_contents;
   Browser* browser = chrome::FindBrowserWithWebContents(web_contents);
   if (!browser)
     return;
@@ -87,6 +87,9 @@ void TabMetricsLoggerImpl::LogBackgroundTab(
   DCHECK_NE(index, TabStripModel::kNoTab);
 
   ukm::builders::TabManager_TabMetrics entry(ukm_source_id);
+  entry.SetKeyEventCount(tab_metrics.page_metrics.key_event_count)
+      .SetMouseEventCount(tab_metrics.page_metrics.mouse_event_count)
+      .SetTouchEventCount(tab_metrics.page_metrics.touch_event_count);
 
   if (SiteEngagementService::IsEnabled())
     entry.SetSiteEngagementScore(GetSiteEngagementScore(web_contents));

chrome/browser/ui/tabs/tab_metrics_logger_impl.h

@@ -18,7 +18,7 @@ class TabMetricsLoggerImpl : public TabMetricsLogger {
 
   // TabMetricsLogger:
   void LogBackgroundTab(ukm::SourceId ukm_source_id,
-                        content::WebContents* web_contents) override;
+                        const TabMetrics& tab_metrics) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TabMetricsLoggerImpl);

tools/metrics/ukm/ukm.xml

@@ -2072,12 +2072,27 @@ be describing additional metrics about the same event.
       Boolean value indicating whether the tab is pinned in the tabstrip.
     </summary>
   </metric>
+  <metric name="KeyEventCount">
+    <summary>
+      Number of key events that were sent to the page.
+    </summary>
+  </metric>
+  <metric name="MouseEventCount">
+    <summary>
+      Number of mouse events that were sent to the page.
+    </summary>
+  </metric>
   <metric name="SiteEngagementScore">
     <summary>
       Site engagement score in the range [0, 100], rounded down to a multiple of
       10 to limit granularity.
     </summary>
   </metric>
+  <metric name="TouchEventCount">
+    <summary>
+      Number of touch events that were sent to the page.
+    </summary>
+  </metric>
 </event>
 
 </ukm-configuration>