[Extensions] Enable promise support on the cookies API

This CL changes over the json schema to use the new returns_async format
to define callbacks, enabling promise support on those APIs.

Bug: 328932
Change-Id: I6b2f545c3b3b92e30a1a355256a17083e12c2e3c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2515141Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Tim Judkins <tjudkins@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826840}

chrome/common/extensions/api/cookies.json

@@ -66,9 +66,9 @@
           {
             "name": "details",
             "$ref": "CookieDetails"
-          },
-          {
-            "type": "function",
+          }
+        ],
+        "returns_async": {
           "name": "callback",
           "parameters": [
             {
@@ -76,7 +76,6 @@
             }
           ]
         }
-        ]
       },
       {
         "name": "getAll",
@@ -96,9 +95,9 @@
               "session": {"type": "boolean", "optional": true, "description": "Filters out session vs. persistent cookies."},
               "storeId": {"type": "string", "optional": true, "description": "The cookie store to retrieve cookies from. If omitted, the current execution context's cookie store will be used."}
             }
-          },
-          {
-            "type": "function",
+          }
+        ],
+        "returns_async": {
           "name": "callback",
           "parameters": [
             {
@@ -106,7 +105,6 @@
             }
           ]
         }
-        ]
       },
       {
         "name": "set",
@@ -129,9 +127,9 @@
               "expirationDate": {"type": "number", "optional": true, "description": "The expiration date of the cookie as the number of seconds since the UNIX epoch. If omitted, the cookie becomes a session cookie."},
               "storeId": {"type": "string", "optional": true, "description": "The ID of the cookie store in which to set the cookie. By default, the cookie is set in the current execution context's cookie store."}
             }
-          },
-          {
-            "type": "function",
+          }
+        ],
+        "returns_async": {
           "name": "callback",
           "optional": true,
           "min_version": "11.0.674.0",
@@ -141,7 +139,6 @@
             }
           ]
         }
-        ]
       },
       {
         "name": "remove",
@@ -151,9 +148,9 @@
           {
             "name": "details",
             "$ref": "CookieDetails"
-          },
-          {
-            "type": "function",
+          }
+        ],
+        "returns_async": {
           "name": "callback",
           "optional": true,
           "min_version": "11.0.674.0",
@@ -171,15 +168,13 @@
             }
           ]
         }
-        ]
       },
       {
         "name": "getAllCookieStores",
         "type": "function",
         "description": "Lists all existing cookie stores.",
-        "parameters": [
-          {
-            "type": "function",
+        "parameters": [],
+        "returns_async": {
           "name": "callback",
           "parameters": [
             {
@@ -187,7 +182,6 @@
             }
           ]
         }
-        ]
       }
     ],
     "events": [