Implement experimental.contentSettings.misc.blockThirdPartyCookies.

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 4519 matching lines @@
                 "properties": {
                   "login": { "type": "string", "optional": true },
                   "token": { "type": "string", "optional": true }
                 }
               }
             ]
           }
         ]
       }
     ]
+  },
+  {
+    "namespace": "experimental.extension",
+    "types": [
+      {
+        "id": "Preference",
+        "type": "object",
+        "description": "An object which allows access to a preference.",
+        "functions": [
+          {
+            "name": "get",
+            "type": "function",
+            "description": "Get the setting from the user preferences.",
+            "parameters": [
+              {
+                "name": "details",
+                "type": "object",
+                "description": "What setting to return.",
+                "properties": {
+                  "incognito": {
+                    "type": "boolean",
+                    "optional": true,
+                    "description": "Whether to return the setting that applies to the incognito session only (default false)."
+                  }
+                }
+              },
+              {
+                "name": "callback",
+                "type": "function",
+                "parameters": [
+                  {
+                    "name": "value",
+                    "description": "The value of the preference.",
+                    "type": "any"

[Aaron Boodman, 2011/02/11 18:33:19]

Can it really be any? I think maybe it can only be string, number, or boolean?
If you make this more strict, the extension system will add extra checking in
debug mode to help us catch situations where the C++ returns the wrong type.

It also helps a bit with the documentation.

[Bernhard Bauer, 2011/02/13 18:19:12]

The preference system itself allows any sort of |Value|. For a specific
preference, we'd have to list the type in its description.

+                  }
+                ]
+              }
+            ]
+          },
+          {
+            "name": "set",
+            "type": "function",
+            "description": "Set the setting in the user preferences",
+            "parameters": [
+              {
+                "name": "details",
+                "type": "object",
+                "description": "What setting to change.",
+                "properties": {
+                  "value": {
+                    "description": "The value of the preference.",
+                    "type": "any"
+                  },
+                  "incognito": {
+                    "type": "boolean",
+                    "optional": true,
+                    "description": "Whether to modify the setting for the incognito session only (default false)."
+                  }
+                }
+              },
+              {
+                "name": "callback",
+                "type": "function",
+                "description": "Called after the preference has been set.",
+                "optional": true,
+                "parameters": []
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  },
+  {
+    "namespace": "experimental.contentSettings.misc",
+    "properties": {
+      "blockThirdPartyCookies": {
+        "$ref": "Preference",
+        "description": "Whether third party cookies should be blocked."

[Aaron Boodman, 2011/02/11 18:33:19]

If you go with this system of reusing the Preference object, you should specify
in each usage what type the preference wants (eg boolean).

[Bernhard Bauer, 2011/02/13 18:19:12]

Done.

+      }
+    }
   }
 ]