<webview>: Update format for local file access in manifest.json

The new format is:


"webview" : {
   "partitions" : [
      {
           "name" : "foo*",
           "accessible_resources" : ["a.html", "b.html"]
      },
      {
           "name" : "bar",
           "accessible_resources" : ["a.html", "c.html"]
      }
   ]
}

BUG=340291

Review URL: https://codereview.chromium.org/151923005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249640 0039d316-1c4b-4281-b951-d872f2087c98
const WebviewInfo* GetResourcesInfo(
    const Extension& extension) {
  return static_cast<WebviewInfo*>(
      extension.GetManifestData(keys::kWebviewAccessibleResources));
}

const WebviewInfo* GetResourcesInfo(
    const Extension& extension) {
  return static_cast<WebviewInfo*>(
      extension.GetManifestData(keys::kWebviewAccessibleResources));
}
