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

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

 // 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.
 
 #ifndef CHROME_BROWSER_UI_ANDROID_INFOBARS_APP_BANNER_INFOBAR_ANDROID_H_
 #define CHROME_BROWSER_UI_ANDROID_INFOBARS_APP_BANNER_INFOBAR_ANDROID_H_
 
 #include "base/android/scoped_java_ref.h"
 #include "base/macros.h"
 #include "chrome/browser/ui/android/infobars/confirm_infobar.h"
@@ skipping 17 matching lines @@
       const GURL& app_url,
       bool is_webapk);
 
   ~AppBannerInfoBarAndroid() override;
 
   // Called when the installation state of the app may have changed.
   // Updates the InfoBar visuals to match the new state and re-enables controls
   // that may have been disabled.
   void OnInstallStateChanged(int new_state);
 
+  // Called when user clicks the "Add To Homescreen" from the app menu to
+  // install a WebAPK. The banner skips the state of showing "Add To
+  // Homescreen" on the button and jumps to the state of showing "Adding"
+  // and starts the installation.
+  void InstallWebApk(content::WebContents* web_contents);

[gone, 2016/08/31 18:12:46]

I don't think this function belongs here because it's a functional change.  It
even calls through directly to the delegate.  Why don't you just call it on the
delegate from AddToHomeScreenManager::CreateInfobar?  You already have access to
it there.

[Xi Han, 2016/08/31 20:11:48]

Hmm, this call needs to be made after both AppBannerInfobarDelegateAndroid and
AppBannerInfobarAndroid are initialized on Java and C++ sides. This is because
the InstallWebAPK() not only starts the installation, but also updates the texts
on the app banner infobar. However, in CreateInfoBarForWebAPK(), the delegate is
a unique_ptr, and it becomes invalid as long as the infobar is created. So I
can't call InstallWebAPK directly through the delegate, but via infobar and to
the delegate. Beside, I don't want add more hack to the
AppBannerInfobarAndroid.java to make the text is initialized with WebAPK logic
(the "Adding" button). I would like to hear if you have better idea.

[gone, 2016/08/31 20:24:22]

Your change to AppBannerInfoBarAndroid::InstallWebApk() consists only of a call
to delegate()->InstallWebApk(web_contents).  That's called at the very end of
CreateInfobar, where everything has already been built.

Can't you just call

InfoBarDelegate* delegate =
static_cast<AppBannerInfoBarAndroid*>(infobar)->delegate();
static_cast<AppBannerInfoBarDelegate*>(delegate)->InstallWebApk(web_contents);?

[Xi Han, 2016/08/31 20:59:24]

You are right, updated. Thanks:)

+
  private:
   // InfoBarAndroid overrides.
   base::android::ScopedJavaLocalRef<jobject> CreateRenderInfoBar(
       JNIEnv* env) override;
 
   // Native app: Details about the app.
   base::android::ScopedJavaGlobalRef<jobject> japp_data_;
 
   // Web app: URL for the app.
   GURL app_url_;
 
   // Indicates whether the info bar is for installing a WebAPK.
   bool is_webapk_;
 
   base::android::ScopedJavaGlobalRef<jobject> java_infobar_;
 
   DISALLOW_COPY_AND_ASSIGN(AppBannerInfoBarAndroid);
 };
 
 #endif  // CHROME_BROWSER_UI_ANDROID_INFOBARS_APP_BANNER_INFOBAR_ANDROID_H_