Grant origins engagement for having interactions on their notifications.

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 1e23de65ebdafc263e054ab9db8ea91d1f703993..e51c366e5d87e68c97f7a30aa1b2a6fee92f7e7d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -109587,9 +109587,11 @@ from previous Chrome versions.
   <int value="2" label="Mouse down"/>
   <int value="3" label="Tap gesture"/>
   <int value="4" label="Scroll (mouse wheel or touch)"/>
-  <int value="5" label="Media (foreground tab)"/>
-  <int value="6" label="Media (background tab)"/>
+  <int value="5" label="Media (background tab)"/>
+  <int value="6" label="Media (foreground tab)"/>

[Ilya Sherman, 2017/03/16 22:22:35]

Hmm, were these labels simply previously wrong, or did the true semantics
actually change?

[dominickn, 2017/03/16 23:25:03]

It was always just wrong! See the enum in
https://cs.chromium.org/chromium/src/chrome/browser/engagement/site_engagemen...,
which has hidden *before* visible.

   <int value="7" label="Webapp shortcut launch"/>
+  <int value="8" label="First daily engagement"/>
+  <int value="9" label="Notification interaction"/>
 </enum>
 
 <enum name="SiteIsolationMimeType" type="int">