[Chromecast] Turn CastContentWindow into an abstract interface.

chromecast/browser/android/apk/AndroidManifest.xml.jinja2

Index: chromecast/browser/android/apk/AndroidManifest.xml.jinja2
diff --git a/chromecast/browser/android/apk/AndroidManifest.xml.jinja2 b/chromecast/browser/android/apk/AndroidManifest.xml.jinja2
index 01e6497649bcb5d6049eb31a9fff957a76364c40..9e393deefe14b5e56577ab684a54c252582d06ad 100644
--- a/chromecast/browser/android/apk/AndroidManifest.xml.jinja2
+++ b/chromecast/browser/android/apk/AndroidManifest.xml.jinja2
@@ -18,11 +18,12 @@
     <application android:name="org.chromium.chromecast.shell.CastApplication"
                  android:icon="@mipmap/app_icon"
                  android:label="@string/app_name">
-        <activity android:name="org.chromium.chromecast.shell.CastShellActivity"
+        <activity android:name="org.chromium.chromecast.shell.CastWebContentsActivity"
                   android:theme="@style/CastShellTheme"
                   android:exported="true"
                   android:hardwareAccelerated="true"
-                  android:taskAffinity=".CastShellActivity"
+                  android:launchMode="standard"
+                  android:taskAffinity=".CastWebContentsActivity"
                   android:configChanges="orientation|keyboardHidden|keyboard|screenSize"
                   android:excludeFromRecents="true"
                   android:noHistory="true">