GCM: Add Android UMA, and UMA for deleted/collapsed messages

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 199b3e478a992b5a95d4b521681bff681b1bf5f9..c44a180f9caa6313ae37da9743d92ef23c403e81 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -18854,9 +18854,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <histogram name="GCM.DataMessageReceived" units="messages">
   <owner>peter@chromium.org</owner>
   <summary>
-    Number of DATA_MESSAGE messages for registered application IDs and
-    DELETED_MESSAGES messages for any registration ID received from Google Cloud
-    Messaging. Recorded when processing the received message.
+    Number of DATA_MESSAGE messages for registered application IDs received from
+    Google Cloud Messaging. Recorded when processing the received message. Prior
+    to M56 this also counted received DELETED_MESSAGES messages for any
+    registration ID.
+  </summary>
+</histogram>
+
+<histogram name="GCM.DataMessageReceivedHasCollapseKey"
+    enum="BooleanHasCollapseKey">
+  <owner>peter@chromium.org</owner>
+  <summary>
+    Records whether a non-empty collapse_key token is set for each received
+    DATA_MESSAGE message for registered application IDs from Google Cloud
+    Messaging. Recorded while processing the received message.
   </summary>
 </histogram>
 
@@ -18865,8 +18876,18 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>peter@chromium.org</owner>
   <summary>
     Records whether a corresponding registration was found for each received
-    DATA_MESSAGE or DELETED_MESSAGES message from Google Cloud Messaging.
-    Recorded while processing the received message.
+    DATA_MESSAGE message from Google Cloud Messaging. Recorded while processing
+    the received message. Prior to M56 this also counted received
+    DELETED_MESSAGES messages.
+  </summary>
+</histogram>
+
+<histogram name="GCM.DeletedMessagesReceived" units="messages">
+  <owner>peter@chromium.org</owner>
+  <summary>
+    For every DELETED_MESSAGES message received from Google Cloud Messaging for
+    registered application IDs, this records the provided count of how many
+    messages were simultaneously deleted.
   </summary>
 </histogram>
 
@@ -77029,6 +77050,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1" label="Hardware accelerated"/>
 </enum>
 
+<enum name="BooleanHasCollapseKey" type="int">
+  <int value="0" label="No collapse_key"/>
+  <int value="1" label="Has collapse_key"/>
+</enum>
+
 <enum name="BooleanHasCrc" type="int">
   <int value="0" label="No CRC"/>
   <int value="1" label="Has CRC"/>