Fix: long-tapping a WebAPK in recents shows Chrome.

chrome/android/webapk/shell_apk/AndroidManifest.xml

Index: chrome/android/webapk/shell_apk/AndroidManifest.xml
diff --git a/chrome/android/webapk/shell_apk/AndroidManifest.xml b/chrome/android/webapk/shell_apk/AndroidManifest.xml
index 1e40170fd1adb8663aedcdae3d0817fbc044bde5..44c3b871fbf8972631f6473b20f017cedcf54276 100644
--- a/chrome/android/webapk/shell_apk/AndroidManifest.xml
+++ b/chrome/android/webapk/shell_apk/AndroidManifest.xml
@@ -31,6 +31,10 @@
                 <data android:scheme="{{ scope_url_scheme }}" android:host="{{ scope_url_host }}" android:pathPrefix="{{ scope_url_path }}"></data>
             </intent-filter>
         </activity>
+        <activity android:name="org.chromium.webapk.shell_apk.RecentsPlaceholderActivity"
+                  android:theme="@android:style/Theme.Translucent.NoTitleBar"
+                  android:exported="false">
+        </activity>
         <activity android:name="org.chromium.webapk.shell_apk.NotificationSettingsLauncherActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>