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

components/infobars/core/infobar_delegate.h

Index: components/infobars/core/infobar_delegate.h
diff --git a/components/infobars/core/infobar_delegate.h b/components/infobars/core/infobar_delegate.h
index ced38d3371df534b78012c299dee1f9fc5804c17..2d849448707243480070db6be77e1630e0f470d3 100644
--- a/components/infobars/core/infobar_delegate.h
+++ b/components/infobars/core/infobar_delegate.h
@@ -22,6 +22,9 @@ class ThemeInstalledInfoBarDelegate;
 class ThreeDAPIInfoBarDelegate;
 
 #if defined(OS_ANDROID)
+namespace banners {
+class AppBannerInfoBarDelegateAndroid;
+}
 class MediaStreamInfoBarDelegateAndroid;
 class MediaThrottleInfoBarDelegate;
 #endif
@@ -216,6 +219,8 @@ class InfoBarDelegate {
   virtual ThreeDAPIInfoBarDelegate* AsThreeDAPIInfoBarDelegate();
   virtual translate::TranslateInfoBarDelegate* AsTranslateInfoBarDelegate();
 #if defined(OS_ANDROID)
+  virtual banners::AppBannerInfoBarDelegateAndroid*
+      AsAppBannerInfoBarDelegateAndroid();
   virtual MediaStreamInfoBarDelegateAndroid*
   AsMediaStreamInfoBarDelegateAndroid();
   virtual MediaThrottleInfoBarDelegate* AsMediaThrottleInfoBarDelegate();