Log First User Interaction in Page Load Metrics

components/page_load_metrics/browser/page_load_metrics_observer.h

 // Copyright 2015 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 COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 #define COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include "base/macros.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
 #include "content/public/browser/navigation_handle.h"
+#include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "url/gurl.h"
 
 namespace page_load_metrics {
 
 // This enum represents how a page load ends. If the action occurs before the
 // page load finishes (or reaches some point like first paint), then we consider
 // the load to be aborted.
 enum UserAbortType {
   // Represents no abort.
   ABORT_NONE,
@@ skipping 23 matching lines @@
   // navigation it was.
   ABORT_UNKNOWN_NAVIGATION,
 
   // Add values before this final count.
   ABORT_LAST_ENTRY
 };
 
 struct PageLoadExtraInfo {
   PageLoadExtraInfo(base::TimeDelta first_background_time,
                     base::TimeDelta first_foreground_time,
+                    base::TimeDelta first_user_interaction_time,
                     bool started_in_foreground,
                     const GURL& committed_url,
                     base::TimeDelta time_to_commit,
                     UserAbortType abort_type,
                     base::TimeDelta time_to_abort,
                     const PageLoadMetadata& metadata);
   PageLoadExtraInfo(const PageLoadExtraInfo& other);
 
   // The first time that the page was backgrounded since the navigation started.
   // If the page has not been backgrounded this will be base::TimeDelta().
   const base::TimeDelta first_background_time;
 
   // The first time that the page was foregrounded since the navigation started.
   // If the page has not been foregrounded this will be base::TimeDelta().
   const base::TimeDelta first_foreground_time;
 
+  // The first time that the page was given a user input since the navigation
+  // started.
+  const base::TimeDelta first_user_interaction_time;

[Bryan McQuade, 2016/05/18 15:21:50]

i'm actually not sure if this is a generally useful bit of information we want
to be providing in this struct. in particular, if the first interaction happened
before anything was painted (while the screen is blank), is that likely to be
useful to most consumers?

+
   // True if the page load started in the foreground.
   const bool started_in_foreground;
 
   // Committed URL. If the page load did not commit, |committed_url| will be
   // empty.
   const GURL committed_url;
 
   // Time from navigation start until commit. If the page load did not commit,
   // |time_to_commit| will be zero.
   const base::TimeDelta time_to_commit;
@@ skipping 77 matching lines @@
   virtual void OnFirstTextPaint(const PageLoadTiming& timing,
                                 const PageLoadExtraInfo& extra_info) {}
   virtual void OnFirstImagePaint(const PageLoadTiming& timing,
                                  const PageLoadExtraInfo& extra_info) {}
   virtual void OnFirstContentfulPaint(const PageLoadTiming& timing,
                                       const PageLoadExtraInfo& extra_info) {}
   virtual void OnParseStart(const PageLoadTiming& timing,
                             const PageLoadExtraInfo& extra_info) {}
   virtual void OnParseStop(const PageLoadTiming& timing,
                            const PageLoadExtraInfo& extra_info) {}
+
+  // OnUserInteraction is triggered when a new user input is passed in to
+  // web_contents

[tdresser, 2016/05/17 13:24:53]

nit:missing period.

[tdresser, 2016/05/17 13:24:53]

It worries me a bit that these comments don't make it clear what kinds of input
are being monitored.

For example, most touch based games will _never_ trigger this. If touch events
are preventDefaulted, they won't result in a user interaction.

See rbyers.net/paint.html for an example of a page that you can interact with
(drawing with touch), without causing this to register at all.

[Bryan McQuade, 2016/05/18 15:21:50]

yeah, i agree - it seems the WCO hook we are overriding to get this signal isn't
necessarily well understood or well supported, which is worrying. tim, is there
a better canonical source of input events that we should be wiring through
WebContentsObservers to replace the hook we are using currently? I'd like to
make sure we're using a data source that input team feels is giving good data.

+  virtual void OnUserInteraction(blink::WebInputEvent::Type type) {}
 };
 
 }  // namespace page_load_metrics
 
 #endif  // COMPONENTS_PAGE_LOAD_METRICS_BROWSER_PAGE_LOAD_METRICS_OBSERVER_H_