Page Abort Events for relevant navigations

components/page_load_metrics/browser/metrics_web_contents_observer.h

Index: components/page_load_metrics/browser/metrics_web_contents_observer.h
diff --git a/components/page_load_metrics/browser/metrics_web_contents_observer.h b/components/page_load_metrics/browser/metrics_web_contents_observer.h
index cf39dc9bff6e66878fc7c4cdd5f3e4a02d02ff09..fbea58b0565674cffed9c421bd5fd4574928eff9 100644
--- a/components/page_load_metrics/browser/metrics_web_contents_observer.h
+++ b/components/page_load_metrics/browser/metrics_web_contents_observer.h
@@ -52,6 +52,20 @@ enum PageLoadEvent {
   PAGE_LOAD_SUCCESSFUL_FIRST_LAYOUT_FOREGROUND,
   PAGE_LOAD_SUCCESSFUL_FIRST_LAYOUT_BACKGROUND,
 
+  // The user aborted the page load before first layout, and the page is one
+  // that we would have logged first layout info from (e.g. it is http/https,
+  // not same-page, etc.).
+  PAGE_LOAD_RELEVANT_ABORTED_BEFORE_FIRST_LAYOUT,
+
+  // Counts the number of page loads started in foreground / background.
+  PAGE_LOAD_RELEVANT_STARTED_IN_FOREGROUND,
+  PAGE_LOAD_RELEVANT_STARTED_IN_BACKGROUND,
+
+  // A timing IPC was sent from the renderer that did not line up with previous
+  // data we've received (i.e. navigation start is different or the timing
+  // struct is somehow invalid).
+  PAGE_LOAD_BAD_IPC,

[Randy Smith (Not in Mondays), 2015/10/06 19:24:00]

I'd like the comments for these instances to make clear what overlap they have
with the other elements in the list; tracking what's disjoint, what's subset,
and what's just overlapping is getting hard.

Suggestion (up to you): Make separate histograms (and separate enums) where each
histogram has the property that each load shows up in only one bucket.  It might
make the bucket descriptions a bit confusing, but I think it would make analysis
and comparison much easier.

+
   // Add values before this final count.
   PAGE_LOAD_LAST_ENTRY
 };
@@ -62,6 +76,7 @@ class PageLoadTracker {
   ~PageLoadTracker();
   void Commit();
   void WebContentsHidden();
+  void WebContentsShown();
 
   // Returns true if the timing was successfully updated.
   bool UpdateTiming(const PageLoadTiming& timing);
@@ -76,6 +91,7 @@ class PageLoadTracker {
   // because metrics like layout/paint are delayed artificially
   // when they occur in the bacground.
   base::TimeTicks background_time_;
+  base::TimeTicks foreground_time_;
   bool started_in_foreground_;
 
   PageLoadTiming timing_;