diff --git a/types/chrome-apps/index.d.ts b/types/chrome-apps/index.d.ts
index 1becbe95a6..2d63dc6330 100644
--- a/types/chrome-apps/index.d.ts
+++ b/types/chrome-apps/index.d.ts
@@ -6468,13 +6468,11 @@ declare namespace chrome {
     namespace permissions {
         interface Permissions {
             /**
-             * Optional.
              * List of named permissions (does not include hosts or origins).
              * Anything listed here must appear in the optional_permissions list in the manifest.
              */
-            origins?: chrome.runtime.OptionalPermissions[];
+            permissions?: chrome.runtime.OptionalPermission[];
             /**
-             * Optional.
              * List of origin permissions.
              * Anything listed here must be a subset of a host that appears in the
              * optional_permissions list in the manifest. For example, if
@@ -6482,33 +6480,33 @@ declare namespace chrome {
              * you can request an origin of http://help.example.com/.
              * Any path is ignored.
              */
-            permissions?: chrome.runtime.UrlMatches[] | string[];
+            origins?: chrome.runtime.UrlMatches[] | string[];
         }
 
-        interface PermissionEvent extends chrome.events.Event<(permissions: chrome.runtime.Permission[]) => void> { }
+        interface PermissionEvent extends chrome.events.Event<(permissions: Permissions) => void> { }
 
         /**
          * Checks if the app has the specified permissions.
-         * @param callback Parameter result: True if the app has the specified permissions.
+         * @param callback Parameter *result*: True if the app has the specified permissions.
          */
-        function contains(permissions: chrome.runtime.Permission[], callback: (result: boolean) => void): void;
+        function contains(permissions: Permissions, callback: (result: boolean) => void): void;
         /**
          * Gets the app's current set of permissions.
-         * @param callback Parameter permissions: The app's active permissions.
+         * @param callback Parameter *permissions*: The app's active permissions.
          */
-        function getAll(callback: (permissions: chrome.runtime.Permission[]) => void): void;
+        function getAll(callback: (permissions: Permissions) => void): void;
         /**
          * Requests access to the specified permissions.
          * These permissions must be defined in the optional_permissions field of the manifest.
          * If there are any problems requesting the permissions, runtime.lastError will be set.
-         * @param [callback] Parameter granted: True if the user granted the specified permissions.
+         * @param [callback] Parameter *granted*: True if the user granted the specified permissions.
          */
-        function request(permissions: chrome.runtime.Permission[], callback?: (granted: boolean) => void): void;
+        function request(permissions: Permissions, callback?: (granted: boolean) => void): void;
         /**
          * Removes access to the specified permissions. If there are any problems removing the permissions, runtime.lastError will be set.
-         * @param [callback] Parameter removed: True if the permissions were removed.
+         * @param [callback] Parameter *removed*: True if the permissions were removed.
          */
-        function remove(permissions: chrome.runtime.Permission[], callback?: (removed: boolean) => void): void;
+        function remove(permissions: Permissions, callback?: (removed: boolean) => void): void;
 
         /** Fired when access to permissions has been removed from the app. */
         const onRemoved: PermissionEvent;
@@ -6565,7 +6563,7 @@ declare namespace chrome {
              * empty list, however, certificates of any type will be returned.
              * @see ClientCertificateType
              */
-            certificateTypes: ToStringLiteral<typeof ClientCertificateType[]>;
+            certificateTypes: ToStringLiteral<typeof ClientCertificateType>[];
 
             /**
              * List of distinguished names of certificate authorities allowed by the
@@ -7072,12 +7070,11 @@ declare namespace chrome {
             'tts' |
             'wallpaper';
 
-        type OptionalPermission = Exclude<Permission, NotAllowedAsOptionalPermissions>;
         /**
          * Optional permissions
-         * @see NotAllowedAsOptionalPermissions for permissions that you're not allowed to set.
+         * @see NotAllowedAsOptionalPermissions for permissions that you're not allowed to set on demand.
          */
-        type OptionalPermissions = Array<OptionalPermission> | Array<OptionalPermission | string>;
+        type OptionalPermission = Exclude<Permission, NotAllowedAsOptionalPermissions>;
 
         type Permission =
             /** Gives your app access to the chrome.alarms API. */
@@ -7683,7 +7680,7 @@ declare namespace chrome {
              * at run time rather than install time, so users understand why the
              * permissions are needed and grant only those that are necessary.
              */
-            optional_permissions?: OptionalPermissions;
+            optional_permissions?: OptionalPermission[] | Array<OptionalPermission | chrome.runtime.UrlMatches[]> | Array<OptionalPermission | chrome.runtime.UrlMatches[] | string>;
 
             /**
              * Permissions help to limit damage if your app is compromised by malware.
@@ -10630,11 +10627,20 @@ declare namespace chrome {
             SHOW_CONFIGURE_DIALOG: 'showConfigureDialog'
         };
         interface VpnSessionParameters {
-            /** IP address for the VPN interface in CIDR notation. IPv4 is currently the only supported mode. */
+            /**
+             * IP address for the VPN interface in CIDR notation.
+             * IPv4 is currently the only supported mode.
+             */
             address: string;
-            /** Broadcast address for the VPN interface. (default: deduced from IP address and mask) */
+            /**
+             * Broadcast address for the VPN interface.
+             * (default: deduced from IP address and mask)
+             */
             broadcastAddress?: string;
-            /** MTU setting for the VPN interface. (default: 1500 bytes) */
+            /**
+             * MTU setting for the VPN interface (default 1500 bytes).
+             * @default '1500'
+             */
             mtu?: string;
             /**
              * Exclude network traffic to the list of IP blocks in CIDR notation from the tunnel.
@@ -10659,7 +10665,22 @@ declare namespace chrome {
             /** A list of search domains. (default: no search domain) */
             domainSearch?: string[];
             /** A list of IPs for the DNS servers. */
-            dnsServer: string[];
+            dnsServers: string[];
+            /**
+             * @since Chrome 51.
+             * Whether or not the VPN extension implements auto-reconnection.
+             * If true, the *linkDown*, *linkUp*, *linkChanged*, *suspend*, and *resume*
+             * platform messages will be used to signal the respective events.
+             *
+             * If false, the system will forcibly disconnect the VPN if the network
+             * topology changes, and the user will need to reconnect manually.
+             *
+             * This property is new in Chrome 51; it will generate an exception in
+             * earlier versions. try/catch can be used to conditionally enable the
+             * feature based on browser support.
+             * @default false
+             */
+            reconnect: boolean;
         }
 
         /**
@@ -10724,21 +10745,23 @@ declare namespace chrome {
      * @since Chrome 43.
      */
     namespace wallpaper {
-        const WallpaperLayout: {
-            'STRETCH': 'STRETCH',
-            'CENTER': 'CENTER',
-            'CENTER_CROPPED': 'CENTER_CROPPED'
-        };
+        enum WallpaperLayout {
+            STRETCH = 'STRETCH',
+            CENTER = 'CENTER',
+            CENTER_CROPPED = 'CENTER_CROPPED'
+        }
+        type WallpaperLayoutType = 'STRETCH' | 'CENTER' | 'CENTER_CROPPED';
+
         interface WallpaperDetails {
             /** The jpeg or png encoded wallpaper image. */
-            data?: any;
+            data?: ArrayBuffer;
             /** The URL of the wallpaper to be set. */
             url?: string;
             /**
              * The supported wallpaper layouts.
              * @see WallpaperLayout
              */
-            layout: ToStringLiteral<typeof WallpaperLayout>;
+            layout: WallpaperLayout | WallpaperLayoutType;
             /** The file name of the saved wallpaper. */
             filename: string;
             /** True if a 128x60 thumbnail should be generated. */
diff --git a/types/chrome-apps/test/index.ts b/types/chrome-apps/test/index.ts
index a08a6cc833..1831ec90f5 100644
--- a/types/chrome-apps/test/index.ts
+++ b/types/chrome-apps/test/index.ts
@@ -1,3 +1,9 @@
+/**
+ * Some of the tests are based on examples found in the Chromium documentation or source.
+ * @author Nikolai Ommundsen (niikoo {@link https://github.com/niikoo})
+ * @author The Chromium Authors
+ */
+
 import runtime = chrome.app.runtime;
 const cwindow = chrome.app.window;
 
@@ -921,9 +927,116 @@ chrome.networking.onc.getNetworks({ 'networkType': 'All' }, (networkList) => {
 
 chrome.notifications; // @todo TODO Tests
 
-chrome.platformKeys; // @todo TODO Tests
+// #region chrome.platformKeys
 
-chrome.permissions; // @todo TODO Tests
+var data = {
+    trusted_l1_leaf_cert: 'l1_leaf.der',
+    trusted_l1_interm_cert: 'l1_interm.der',
+    trusted_l2_leaf_cert: 'l2_leaf.der',
+    client_1: 'client_1.der',
+    client_2: 'client_2.der',
+    client_1_spki: 'client_1_spki.der',
+    client_1_issuer_dn: {
+        buffer: new ArrayBuffer(16)
+    },
+    raw_data: 'data',
+    signature_nohash_pkcs: 'signature_nohash_pkcs',
+    signature_client1_sha1_pkcs: 'signature_client1_sha1_pkcs',
+    signature_client2_sha1_pkcs: 'signature_client2_sha1_pkcs',
+};
+function requestCA1(): chrome.platformKeys.ClientCertificateRequest {
+    return {
+        certificateTypes: [],
+        certificateAuthorities: [data.client_1_issuer_dn.buffer]
+    };
+}
+chrome.platformKeys.selectClientCertificates(
+    { interactive: false, request: requestCA1() },
+    (matches) => {
+    });
+
+const requestECDSA: chrome.platformKeys.ClientCertificateRequest = {
+    certificateTypes: ['ecdsaSign'],
+    certificateAuthorities: []
+};
+chrome.platformKeys.selectClientCertificates(
+    { interactive: false, request: requestECDSA },
+    (matches) => {
+        return matches.length;
+    });
+
+if (chrome.platformKeys.subtleCrypto &&
+    chrome.platformKeys.subtleCrypto() &&
+    chrome.platformKeys.subtleCrypto().sign &&
+    chrome.platformKeys.subtleCrypto().exportKey) {
+    console.log('Subtle crypto working (Y)')
+}
+
+var keyParams = {
+    // Algorithm names are case-insensitive.
+    name: 'RSASSA-Pkcs1-V1_5',
+    hash: { name: 'sha-1' }
+};
+chrome.platformKeys.getKeyPair(
+    data.client_1_issuer_dn.buffer, keyParams,
+    (publicKey, privateKey) => {
+        let expectedAlgorithm = {
+            modulusLength: 2048,
+            name: "RSASSA-PKCS1-v1_5",
+            publicExponent: new Uint8Array([0x01, 0x00, 0x01]),
+            hash: { name: 'SHA-1' }
+        };
+
+        if (expectedAlgorithm === publicKey.algorithm &&
+            privateKey &&
+            expectedAlgorithm === privateKey.algorithm) {
+            if (publicKey.type === 'public' && privateKey.type === 'private') {
+                console.log('All okay!');
+            }
+        }
+        chrome.platformKeys.subtleCrypto()
+            .exportKey('spki', publicKey)
+            .then((actualPublicKeySpki) => {
+                if (new ArrayBuffer(100) === actualPublicKeySpki) {
+                    return false;
+                }
+            });
+    });
+var details = {
+    serverCertificateChain: [data.client_1_issuer_dn.buffer],
+    hostname: "l1_leaf"
+};
+chrome.platformKeys.verifyTLSServerCertificate(
+    details, (result) => {
+        return result.trusted;
+    });
+// #endregion
+
+// #region chrome.permissions
+
+chrome.permissions.request({ permissions: ['storage'] }, (granted) => {
+    return granted && 'It was granted';
+});
+
+chrome.permissions.getAll((permissions) => {
+    if (chrome.runtime.lastError || !permissions.permissions) {
+        return;
+    }
+    for (const permission of permissions.permissions) {
+        if (permission === 'alarms') {
+            return 'I knew it!';
+        }
+        chrome.permissions.remove({ permissions: [permission] }, (removed) => {
+            return removed ? 'It was removed' : 'It was not removed';
+        });
+    }
+    chrome.permissions.contains({ origins: ['chrome://favicon/'] }, (doIHaveIt) => doIHaveIt ? 'yes' : 'neh');
+    chrome.permissions.request(
+        { permissions: ['audio'] },
+        () => { });
+});
+
+// #endregion
 
 // #region chrome.power
 
@@ -1360,9 +1473,58 @@ chrome.virtualKeyboard.restrictFeatures(
 );
 // #endregion
 
-chrome.vpnProvider; // @todo TODO Tests
-chrome.wallpaper; // @todo TODO Tests
-chrome.webViewRequest; // @todo TODO Tests
+// #region chrome.vpnProvider
+
+const vpnParams = {
+    address: '127.0.0.1/32',
+    mtu: '1500',
+    exclusionList: ['127.0.0.1/32'],
+    inclusionList: ['0.0.0.0/0'],
+    dnsServers: ['1.1.1.1', '1.0.0.1', '8.8.8.8'],
+    reconnect: true
+};
+chrome.vpnProvider.onConfigCreated.addListener((id, name, data) => {
+    console.log('Connected: ', id.toLowerCase(), name.toUpperCase(), JSON.stringify(data));
+});
+chrome.vpnProvider.createConfig('Local VPN', (id) => {
+    chrome.vpnProvider.setParameters(vpnParams, () => {
+        if (chrome.runtime.lastError) {
+            chrome.vpnProvider.notifyConnectionStateChanged('failure');
+            throw chrome.runtime.lastError;
+        }
+        chrome.vpnProvider.notifyConnectionStateChanged('connected', () => {
+            chrome.vpnProvider.onPacketReceived.addListener(data => {
+                return data.byteLength > 0 ? data : undefined;
+            });
+            chrome.vpnProvider.onConfigRemoved.addListener(id => id.toUpperCase());
+            chrome.vpnProvider.onPlatformMessage.addListener((id, message) => {
+                if (typeof id === 'string') {
+                    return message === 'connected';
+                }
+            });
+            chrome.vpnProvider.onUIEvent.addListener((event, id) => {
+                if (event === 'showAddDialog') {
+                    return id;
+                }
+            });
+        });
+    });
+});
+// #endregion
+
+// #region chrome.wallpaper
+chrome.wallpaper.setWallpaper({
+    url: 'chrome://favicon/iconurl/https://www.google.com/favicon.ico',
+    layout: 'CENTER_CROPPED',
+    filename: 'test_wallpaper'
+}, (thumbnail) => {
+    const imageUrl = thumbnail;
+});
+chrome.wallpaper.setWallpaper({
+    layout: chrome.wallpaper.WallpaperLayout.STRETCH,
+    filename: 'test_wallpaper2'
+}, () => { });
+// #endregion
 
 // #region chrome.webViewRequest & WebView