Fix appinstalled event firing when user opens a WebAPK from banner.

The "Open" button was calling SendBannerAccepted, which made the
assumption that the app was being installed. Removed this call and
documented the method's semantics.

BUG=716313

Review-Url: https://codereview.chromium.org/2848703005
Cr-Commit-Position: refs/heads/master@{#467903}

chrome/browser/android/banners/app_banner_infobar_delegate_android.cc

@@ -303,11 +303,10 @@ bool AppBannerInfoBarDelegateAndroid::AcceptWebApk(
   JNIEnv* env = base::android::AttachCurrentThread();
 
   // If the WebAPK is installed and the "Open" button is clicked, open the
-  // WebAPK.
+  // WebAPK. Do not send a BannerAccepted message.
   if (install_state_ == INSTALLED) {
     Java_AppBannerInfoBarDelegateAndroid_openWebApk(env, java_delegate_);
     webapk::TrackUserAction(webapk::USER_ACTION_INSTALLED_OPEN);
-    SendBannerAccepted();
     return true;
   }
 

chrome/browser/android/banners/app_banner_infobar_delegate_android.h

@@ -122,6 +122,10 @@ class AppBannerInfoBarDelegateAndroid : public ConfirmInfoBarDelegate {
   // Returns false if this delegate is for a WebAPK and was triggered from the
   // A2HS menu item. Otherwise returns true.
   bool TriggeredFromBanner() const;
+
+  // Called when the user accepts the banner to install the app. (Not called
+  // when the "Open" button is pressed on the banner that is shown after
+  // installation for WebAPK banners.)
   void SendBannerAccepted();
   void OnWebApkInstallFinished(WebApkInstallResult result,
                                bool relax_updates,