Mark WebView as Android TV compatible.

Android apps must declare the android.software.leanback feature to
indicate that they are compatible with Android TV (and can specify
required="false" to indicate that they are also compatible with non-TV
devices). Declare this for WebView, which is used on TV devices.

https://developer.android.com/training/tv/start/start#leanback-req
describes this requirement in detail.

Silence the MissingLeanbackLauncher lint warning; WebView doesn't have a
launcher on non-TVs either, so this is expected.

Bug: 870010
Change-Id: Id07ecf06f50d1247639e4e32ea0128d68376a633
Reviewed-on: https://chromium-review.googlesource.com/1178801
Commit-Queue: Richard Coles <torne@chromium.org>
Reviewed-by: Changwan Ryu <changwan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583845}

android_webview/apk/java/AndroidManifest.xml

@@ -7,13 +7,16 @@
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
-    package="{{package|default('com.android.webview')}}">
+    package="{{package|default('com.android.webview')}}"
+    tools:ignore="MissingLeanbackLauncher">
     <uses-sdk android:minSdkVersion="{{minsdk|default(21)}}"
               android:targetSdkVersion="{{targetsdk|default(28)}}">
     </uses-sdk>
 
     <uses-feature android:name="android.hardware.touchscreen"
                   android:required="false" />
+    <uses-feature android:name="android.software.leanback"
+                  android:required="false" />
 
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />