Improve tracking of user initiated page loads.

chrome/browser/page_load_metrics/page_load_tracker.h

Index: chrome/browser/page_load_metrics/page_load_tracker.h
diff --git a/chrome/browser/page_load_metrics/page_load_tracker.h b/chrome/browser/page_load_metrics/page_load_tracker.h
index 3d082f8e03afa7c0d96e3f9436edf8d6057e0160..46e60fda771c6891c4d5a9ca6efc8cc7a7d3ceef 100644
--- a/chrome/browser/page_load_metrics/page_load_tracker.h
+++ b/chrome/browser/page_load_metrics/page_load_tracker.h
@@ -247,9 +247,8 @@ class PageLoadTracker {
   // be the first abort action the user performed.
   UserAbortType abort_type_;
 
-  // This boolean is only an approximation. As the aborts pipeline is updated,

[Bryan McQuade, 2016/11/10 15:51:22]

I changed this comment as I feel this kind of comment is really more about the
limitations of user initiated navigation tracking in general than it is specific
to user-initiated abort tracking.

The 'this is only set for navigations aborting navigations' also isn't totally
accurate anymore now that a page backgrounding can cause an abort with an abort
type of 'background' so I removed it.

[Charlie Harrison, 2016/11/10 20:33:04]

I'd like the comment to remain general, as it is important that we eventually
distinguish e.g. non-navigational aborts as user initiated or not (i.e. tab
close vs process OOM).

[Bryan McQuade, 2016/11/10 20:58:18]

Makes sense. I updated the comment to be a little more specific, and to reflect
the change that we now track some non-nav-related user initiated aborts.

-  // more abort types will have this set to true. Currently, this is only set
-  // for navigations aborting navigations.
+  // Whether the page load that aborted this page load was user initiated. Only
+  // set if this page load's abort type is set to a value other than ABORT_NONE.
   bool abort_user_initiated_;
 
   base::TimeTicks abort_time_;
@@ -274,7 +273,7 @@ class PageLoadTracker {
 
   // This is derived from the user gesture bit in the renderer. For browser
   // initiated navigations this will always be true.
-  bool user_gesture_;
+  bool user_initiated_;
 
   // This is a subtle member. If a provisional load A gets aborted by
   // provisional load B, which gets aborted by C that eventually commits, then