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

chrome/android/webapk/shell_apk/AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2015 The Chromium Authors. All rights reserved.
      Use of this source code is governed by a BSD-style license that can be
      found in the LICENSE file.
 -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     package="{{ manifest_package }}"
     android:versionCode="{{ version_code }}"
     android:versionName="{{ version_name }}" >
@@ skipping 13 matching lines @@
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
             <intent-filter>
                 <action android:name="android.intent.action.VIEW"></action>
                 <category android:name="android.intent.category.DEFAULT"></category>
                 <category android:name="android.intent.category.BROWSABLE"></category>
                 <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"/>
                 <category android:name="android.intent.category.NOTIFICATION_PREFERENCES"/>
             </intent-filter>
         </activity>
         <meta-data android:name="org.chromium.webapk.shell_apk.shellApkVersion" android:value="{{ shell_apk_version }}" />
         <meta-data android:name="org.chromium.webapk.shell_apk.runtimeHost" android:value="{{ runtime_host }}" />
         <meta-data android:name="org.chromium.webapk.shell_apk.startUrl" android:value="{{ start_url }}" />
         <meta-data android:name="org.chromium.webapk.shell_apk.name" android:value="{{ name }}" />
@@ skipping 29 matching lines @@
             android:process=":webapk_sandboxed_process1"
             android:exported="true"
             tools:ignore="ExportedService"/>
         <service android:name="org.chromium.webapk.shell_apk.WebApkSandboxedProcessService2"
             android:isolatedProcess="true"
             android:process=":webapk_sandboxed_process2"
             android:exported="true"
             tools:ignore="ExportedService"/>
     </application>
 </manifest>