Record web push message payload size

Bug: 974816
Change-Id: I0375b88459de729de40d13e96a80caa159d5b5d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1710570Reviewed-by: Peter Beverloo <peter@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Alex Chau <alexchau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680011}

components/gcm_driver/web_push_metrics.cc

@@ -12,4 +12,9 @@ void LogSendWebPushMessageResult(SendWebPushMessageResult result) {
   base::UmaHistogramEnumeration("GCM.SendWebPushMessageResult", result);
 }
 
+void LogSendWebPushMessagePayloadSize(int size) {
+  // Note: The maximum size accepted by FCM is 4096.
+  base::UmaHistogramCounts10000("GCM.SendWebPushMessagePayloadSize", size);
+}
+
 }  // namespace gcm

components/gcm_driver/web_push_metrics.h

@@ -23,6 +23,10 @@ enum class SendWebPushMessageResult {
 // is sent.
 void LogSendWebPushMessageResult(SendWebPushMessageResult result);
 
+// Logs the size of message payload to UMA. This should be called right before a
+// web push message is sent.
+void LogSendWebPushMessagePayloadSize(int size);
+
 }  // namespace gcm
 
 #endif  // COMPONENTS_GCM_DRIVER_WEB_PUSH_METRICS_H_

components/gcm_driver/web_push_sender.cc

@@ -149,6 +149,7 @@ void WebPushSender::SendMessage(const std::string& fcm_token,
     return;
   }
 
+  LogSendWebPushMessagePayloadSize(message.payload.size());
   std::unique_ptr<network::SimpleURLLoader> url_loader = BuildURLLoader(
       fcm_token, message.time_to_live, *auth_header, message.payload);
   url_loader->DownloadToString(

tools/metrics/histograms/histograms.xml

@@ -45656,6 +45656,15 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="GCM.SendWebPushMessagePayloadSize" expires_after="2020-02-02">
+  <owner>alexchau@chromium.org</owner>
+  <owner>peter@chromium.org</owner>
+  <summary>
+    Size of web push messages payload. Recorded right before the message is
+    sent.
+  </summary>
+</histogram>
+
 <histogram name="GCM.SendWebPushMessageResult" enum="SendWebPushMessageResult"
     expires_after="2020-02-02">
   <owner>alexchau@chromium.org</owner>