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..5faf238266e34c03130d5e3888389e10ffb94852 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -18851,12 +18851,23 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="GCM.DataMessageReceived" units="messages">
+<histogram name="GCM.DataMessageReceived" enum="BooleanReceived">
   <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 received from Google Cloud Messaging for
+    which a matching registration exists. Recorded when processing the received
+    message. Prior to M56 this also counted received DELETED_MESSAGES messages
+    (whether or not a registration existed).
+  </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 from Google Cloud Messaging for which a matching
+    registration exists. Recorded while processing the received message.
   </summary>
 </histogram>
 
@@ -18864,9 +18875,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     enum="BooleanRegistered">
   <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.
+    Records whether a matching registration was found for each received
+    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
+    (whether or not a matching registration exists), this records the provided
+    count of how many messages were simultaneously deleted, or zero if the count
+    is unknown.
   </summary>
 </histogram>
 
@@ -77029,6 +77051,11 @@ 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"/>