Revert "Speculative revert by sheriff"

content/child/notifications/notification_manager.cc

Index: content/child/notifications/notification_manager.cc
diff --git a/content/child/notifications/notification_manager.cc b/content/child/notifications/notification_manager.cc
index 96963df004cd40ad0f91db3c73f58006809e871b..b442bafb2eaa8b2ee3aedb14a587c05cbce6247c 100644
--- a/content/child/notifications/notification_manager.cc
+++ b/content/child/notifications/notification_manager.cc
@@ -4,7 +4,10 @@
 
 #include "content/child/notifications/notification_manager.h"
 
+#include <cmath>
+
 #include "base/lazy_instance.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/thread_task_runner_handle.h"
@@ -95,6 +98,24 @@ void NotificationManager::showPersistent(
           service_worker_registration)->registration_id();
 
   scoped_ptr<blink::WebNotificationShowCallbacks> owned_callbacks(callbacks);
+
+  // Verify that the author-provided payload size does not exceed our limit.
+  // This is an implementation-defined limit to prevent abuse of notification
+  // data as a storage mechanism. A UMA histogram records the requested sizes,
+  // which enables us to track how much data authors are attempting to store.
+  //
+  // If the size exceeds this limit, reject the showNotification() promise. This
+  // is outside of the boundaries set by the specification, but it gives authors
+  // an indication that something has gone wrong.
+  size_t author_data_size = notification_data.data.size();
+  UMA_HISTOGRAM_MEMORY_KB("Notifications.AuthorDataSizeKB",
+                          static_cast<int>(ceil(author_data_size / 1024.0)));
+
+  if (author_data_size > PlatformNotificationData::kMaximumDeveloperDataSize) {
+    owned_callbacks->onError();
+    return;
+  }
+
   if (notification_data.icon.isEmpty()) {
     DisplayPersistentNotification(origin,
                                   notification_data,