tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 977e434e879b4d648003c9d3400c327196a90463..47b6e2d305e5986aae1b36d4f92cfbb113c9a5cc 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -196,6 +196,10 @@ other types of suffix sets.
   <summary>Interactions with the App Launcher promo dialog.</summary>
 </histogram>
 
+<histogram name="Apps.AppListHowEnabled" enum="AppListEnableSource">
+  <summary>The trigger that caused the app list to be enabled.</summary>

[Alexei Svitkine (slow), 2014/02/11 15:43:46]

Please expand description to make it clear when this is logged (e.g. is it
logged when app list becomes enabled or is it logged at startup for startups
where app list is on?).

[tapted, 2014/02/12 22:51:21]

Done.

+</histogram>
+
 <histogram name="Apps.AppListSearchCommenced" units="searches">
   <summary>
     The number of searches that are started in the app list. This is gathered
@@ -210,6 +214,16 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Apps.AppListTimeToDiscover" units="seconds">

[Alexei Svitkine (slow), 2014/02/11 15:43:46]

Per the client code, the units will not be seconds, since you're logging the
time delta directly. I believe the way you're logging it now, it will be
milliseconds.

[tapted, 2014/02/12 22:51:21]

Done. +double-checked with --v=1.

Thanks for checking - I had actually assumed this was just a formatting guide,
since FactoryTimeGet only took TimeDelta (i.e. specifying `milliseconds` would
just drop zeros when displaying the histogram, still keeping the raw data
unchanged).

+  <summary>
+    Time between enabling the app list, and a user explicitly choosing to show
+    it. If the app list is not shown after one hour, an entry in the last bucket
+    is recorded. If the user installs a second packaged app within one hour, or
+    if the app list was not enabled by installing a packaged app from the Web
+    Store, no time value is recorded - only Apps.AppListHowEnabled.
+  </summary>
+</histogram>
+
 <histogram name="Ash.ActiveTouchPoints">
   <summary>
     Number of active touch-points when a new touch-point is added.
@@ -22612,6 +22626,15 @@ other types of suffix sets.
   <int value="3" label="Learn more"/>
 </enum>
 
+<enum name="AppListEnableSource" type="int">
+  <int value="0" label="Not enabled (should never be recorded)"/>
+  <int value="1" label="Packaged app installed from Web Store"/>
+  <int value="2" label="Clicked app launcher link from the Web Store"/>
+  <int value="3" label="Command line flag"/>
+  <int value="4" label="Chrome reinstalled over old, enabled profile"/>
+  <int value="5" label="Second packaged app installed without showing"/>
+</enum>
+
 <enum name="AppListSearchResult" type="int">
   <int value="0" label="OMNIBOX"/>
   <int value="1" label="APP"/>