Merge m-c to autoland, a=merge

dom/base/nsFrameMessageManager.cpp

@@ -663,6 +663,7 @@ nsFrameMessageManager::SendMessage(const nsAString& aMessageName,
 
   nsTArray<StructuredCloneData> retval;
 
+  TimeStamp start = TimeStamp::Now();
   sSendingSyncMessage |= aIsSync;
   bool ok = mCallback->DoSendBlockingMessage(aCx, aMessageName, data, objects,
                                              aPrincipal, &retval, aIsSync);
@@ -670,6 +671,17 @@ nsFrameMessageManager::SendMessage(const nsAString& aMessageName,
     sSendingSyncMessage = false;
   }
 
+  uint32_t latencyMs = round((TimeStamp::Now() - start).ToMilliseconds());
+  if (latencyMs >= kMinTelemetrySyncMessageManagerLatencyMs) {
+    NS_ConvertUTF16toUTF8 messageName(aMessageName);
+    // NOTE: We need to strip digit characters from the message name in order to
+    // avoid a large number of buckets due to generated names from addons (such
+    // as "ublock:sb:{N}"). See bug 1348113 comment 10.
+    messageName.StripChars("0123456789");
+    Telemetry::Accumulate(Telemetry::IPC_SYNC_MESSAGE_MANAGER_LATENCY_MS,
+                          messageName, latencyMs);
+  }
+
   if (!ok) {
     return NS_OK;
   }