Trigger app banner when add to homescreen is pressed and WebAPKs are enabled.

chrome/browser/ui/android/infobars/app_banner_infobar_android.cc

 // 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.
 
 #include "chrome/browser/ui/android/infobars/app_banner_infobar_android.h"
 
 #include <utility>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
@@ skipping 55 matching lines @@
   java_infobar_.Reset(env, infobar.obj());
   return infobar;
 }
 
 void AppBannerInfoBarAndroid::OnInstallStateChanged(int new_state) {
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_AppBannerInfoBarAndroid_onInstallStateChanged(env, java_infobar_,
                                                      new_state);
 }
 
+void AppBannerInfoBarAndroid::InstallWebApk(
+    content::WebContents* web_contents) {
+  static_cast<banners::AppBannerInfoBarDelegateAndroid*>(GetDelegate())
+      ->InstallWebApk(web_contents);
+}