Add a new WebAPK-specific app banner shortcut source.

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 6df32d06dc7371157274dd9a4dcebbf2f7768159..b70fbb1145c85c4071ce6a5c8b9c306227ad2fa1 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -24822,11 +24822,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     Chrome.
 
     The Menu item bucket is deprecated as of M57, and will only contain records
-    up until M56.
+    for shortcuts added to the homescreen until M56.
 
     For M57+, the Menu item (standalone) bucket contains all launch intents
     originating from the add to homescreen menu item that launch to standalone
-    mode and *are not* PWAs. These are sites which do not meet the PWA
+    mode and *are not* WebAPKs. These are sites which do not meet the PWA
     eligibility criteria, but have an app manifest that specifies either
     standalone or fullscreen display. This bucket also contains PWA *and*
     non-PWA intents that were added to the homescreen *prior* to M57, as we
@@ -100382,14 +100382,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <enum name="LaunchFromHomeScreenSource" type="int">
   <int value="0" label="Unknown"/>
   <int value="1" label="Menu item (deprecated in M57+)"/>
-  <int value="2" label="App banner"/>
+  <int value="2" label="App banner (non-WebAPK)"/>
   <int value="3" label="Bookmark navigator widget"/>
   <int value="4" label="Bookmark shortcut widget"/>
   <int value="5" label="Notification"/>
-  <int value="6" label="Menu item (PWA)"/>
-  <int value="7" label="Menu item (standalone)"/>
+  <int value="6" label="Menu item (WebAPK)"/>
+  <int value="7" label="Menu item (standalone/legacy PWA)"/>
   <int value="8" label="Menu item (shortcut)"/>
   <int value="9" label="External intent"/>

[pkotwicz, 2017/05/04 17:38:15]

Might as well comment that this one has to do with WebAPKs

[dominickn, 2017/05/05 02:30:40]

Done.

+  <int value="10" label="App banner (WebAPK)"/>
 </enum>
 
 <enum name="LaunchIntentFlags" type="int">