Linux native notifications: Add server capabilities metrics

chrome/browser/notifications/native_notification_display_service.cc

Index: chrome/browser/notifications/native_notification_display_service.cc
diff --git a/chrome/browser/notifications/native_notification_display_service.cc b/chrome/browser/notifications/native_notification_display_service.cc
index 6627fe51fba86c7a55e45de972ab81063797d44a..cba8f8938ce2e578a1fde796b0832291a5b10367 100644
--- a/chrome/browser/notifications/native_notification_display_service.cc
+++ b/chrome/browser/notifications/native_notification_display_service.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/nullable_string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
@@ -66,6 +67,13 @@ NativeNotificationDisplayService::~NativeNotificationDisplayService() = default;
 
 void NativeNotificationDisplayService::OnNotificationPlatformBridgeReady(
     bool success) {
+// If NotificationPlatformBridge initialization succeeded, use
+// native notifications, otherwise fallback to using the Chrome
+// message center.

[Peter Beverloo, 2017/05/02 14:15:24]

Did `git cl format` do this? These should be indented by two spaces..

[Tom (Use chromium acct), 2017/05/02 18:49:41]

Done.

+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+  UMA_HISTOGRAM_BOOLEAN("Linux.NativeNotifications.UsingNativeNotifications",

[Peter Beverloo, 2017/05/02 14:15:24]

What about using:
    Notifications.UsingNativeNotificationCenter

Then we'd be able to re-use it for Windows as well.

[Tom (Use chromium acct), 2017/05/02 18:49:41]

Done.

+                        success);
+#endif
   if (success) {
     notification_bridge_ready_ = true;
   } else {