Add an experimental permissions API for extensions.

chrome/common/extensions/api/extension_api.json

 [
   {
     "namespace": "extension",
     "unprivileged": true,
     "types": [
       {
         "id": "MessageSender",
         "type": "object",
         "description": "An object containing information about the script context that sent a message or request.",
         "properties": {
@@ skipping 1042 matching lines @@
         "name": "onFocusChanged",
         "type": "function",
         "description": "Fired when the currently focused window changes. Will be chrome.windows.WINDOW_ID_NONE if all chrome windows have lost focus. Note: On some Linux window managers, WINDOW_ID_NONE will always be sent immediately preceding a switch from one chrome window to another.",
         "parameters": [
           {"type": "integer", "name": "windowId", "minimum": 0, "description": "ID of the newly focused window."}
         ]
       }
     ]
   },
   {
+    "namespace": "experimental.permissions",
+    "types": [
+      {
+        "id": "Permissions",
+        "type": "object",
+        "properties": {
+          "permissions": {
+            "type": "array",
+            "items": {"type": "string"},
+            "optional": true,
+            "description": "List of named permissions (does not include hosts or origins)."
+          }
+        }
+      }
+    ],
+    "events": [
+      {
+        "name": "onAdded",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Fired when the extension acquires new permissions.",
+        "parameters": [
+          {
+            "$ref": "Permissions",
+            "name": "permissions",
+            "description": "The newly acquired permissions."
+          }
+        ]
+      },
+      {
+        "name": "onRemoved",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Fired when access to permissions has been removed from the extension.",
+        "parameters": [
+          {
+            "$ref": "Permissions",
+            "name": "permissions",
+            "description": "The permissions that have been removed."
+          }
+        ]
+      }
+     ],
+    "functions": [
+      {
+        "name": "getAll",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Gets the extension's current set of permissions.",
+        "parameters": [
+          {
+            "name": "callback",
+            "type": "function",
+            "parameters": [
+               {
+                "name": "permissions",
+                "$ref": "Permissions",
+                "description": "The extension's active permissions."
+              }
+            ]
+          }
+        ]
+      },
+      {
+        "name": "contains",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Checks if the extension has the specified permissions.",
+        "parameters": [
+          {
+            "name": "permissions",
+            "$ref": "Permissions"
+          },
+          {
+            "name": "callback",
+            "type": "function",
+            "parameters": [
+              {
+                "name": "result",
+                "type": "boolean",
+                "description": "True if the extension has the specified permissions."
+              }
+            ]
+          }
+        ]
+      },
+      {
+        "name": "request",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Requests access to the specified permissions. These permissions must be defined in the optional_permissions field of the manifest.",
+        "parameters": [
+          {
+            "name": "permissions",
+            "$ref": "Permissions"
+          },
+          {
+            "name": "callback",
+            "type": "function",
+            "optional": true,
+            "parameters": [
+              {
+                "name": "granted",
+                "type": "boolean",
+                "description": "True if the user granted the specified permissions."
+              }
+            ]
+          }
+        ]
+      },
+      {
+        "name": "remove",
+        "type": "function",
+        "unprivileged": true,
+        "description": "Removes access to the specified permissions.",
+        "parameters": [
+          {
+            "name": "permissions",
+            "$ref": "Permissions"
+          },
+          {
+            "name": "callback",
+            "type": "function",
+            "optional": true,
+            "parameters": [
+              {
+                "name": "removed",
+                "type": "boolean",
+                "description": "True if the permissions were removed."
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  },
+  {
     "namespace": "tabs",
     "types": [
       {
         "id": "Tab",
         "type": "object",
         "properties": {
           "id": {"type": "integer", "minimum": 0, "description": "The ID of the tab. Tab IDs are unique within a browser session."},
           "index": {"type": "integer", "minimum": 0, "description": "The zero-based index of the tab within its window."},
           "windowId": {"type": "integer", "minimum": 0, "description": "The ID of the window the tab is contained within."},
           "selected": {"type": "boolean", "description": "Whether the tab is selected."},
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                 "description": "A string result code. The value is non-empty on success only in tests.",
                 "optional": "true"
               }
             ]
           }
         ]
       }
     ]
   }
 ]