Define the storage API throttling constants in storage.json so that they are

chrome/common/extensions/api/storage.json

Index: chrome/common/extensions/api/storage.json
diff --git a/chrome/common/extensions/api/storage.json b/chrome/common/extensions/api/storage.json
index 1b9b298eeed415e8c58cf83a4803b2841c4755fa..6d9f0f089b5a27b5acb8be4ce930634628eb0b56 100644
--- a/chrome/common/extensions/api/storage.json
+++ b/chrome/common/extensions/api/storage.json
@@ -185,6 +185,14 @@
           "MAX_ITEMS": {
             "value": 512,
             "description": "The maximum number of items that can be stored in sync storage."
+          },
+          "MAX_WRITE_OPERATIONS_PER_HOUR": {
+            "value": 1000,
+            "description": "The maximum number of <code>set</code>, <code>remove</code>, or <code>clear</code> operations that can be performed each hour."
+          },
+          "MAX_SUSTAINED_WRITE_OPERATIONS_PER_MINUTE": {
+            "value": 10,
+            "description": "The maximum number of <code>set</code>, <code>remove</code>, or <code>clear</code> operations that can be performed each minute, sustained over 10 minutes."
           }
         }
       },