Don't expose Picture-in-Picture API for Android WebView.

Picture-in-Picture API is disabled in Android WebView as there is no UI
implemented.

Bug: 855270, 852449
Change-Id: Id7c0ebcc94085f6e1b3f00383254780a5357269b
Reviewed-on: https://chromium-review.googlesource.com/1112247
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Reviewed-by: Tim Volodine <timvolodine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570352}

android_webview/tools/system_webview_shell/test/data/webexposed/not-webview-exposed.txt

@@ -86,6 +86,23 @@ interface PublicKeyCredential : Credential
 interface AuthenticatorResponse
 interface AuthenticatorAttestationResponse : AuthenticatorResponse
 
+# Picture-in-Picture API is disabled in Android WebView, crbug.com/852449
+interface PictureInPictureWindow : EventTarget
+interface Document : Node
+    method exitPictureInPicture
+    getter pictureInPictureElement
+    getter pictureInPictureEnabled
+interface ShadowRoot : DocumentFragment
+    getter pictureInPictureElement
+interface HTMLVideoElement : HTMLMediaElement
+    getter disablePictureInPicture
+    setter disablePictureInPicture
+    method requestPictureInPicture
+    getter onenterpictureinpicture
+    setter onenterpictureinpicture
+    getter onleavepictureinpicture
+    setter onleavepictureinpicture
+
 [GLOBAL OBJECT]
     method openDatabase
     attribute eventSender                    # test only