Create a skeleton AppBannerManager class

chrome/android/java/src/org/chromium/chrome/browser/TabBase.java

Index: chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java b/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
index 357b4fa7fbb3fbd22acc6dde60718e400c15180a..793356e8ddcaf867a54d03837fc11c22075b88a2 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
@@ -13,6 +13,7 @@ import android.view.View;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.ObserverList;
+import org.chromium.chrome.browser.banners.AppBannerManager;
 import org.chromium.chrome.browser.contextmenu.ChromeContextMenuItemDelegate;
 import org.chromium.chrome.browser.contextmenu.ChromeContextMenuPopulator;
 import org.chromium.chrome.browser.contextmenu.ContextMenuParams;
@@ -87,6 +88,9 @@ public abstract class TabBase implements NavigationClient {
     /** InfoBar container to show InfoBars for this tab. */
     private InfoBarContainer mInfoBarContainer;
 
+    /** Manages app banners shown for this tab. */
+    private AppBannerManager mAppBannerManager;
+
     /** The sync id of the TabBase if session sync is enabled. */
     private int mSyncId;
 
@@ -671,6 +675,12 @@ public abstract class TabBase implements NavigationClient {
         } else {
             mInfoBarContainer.onParentViewChanged(getId(), getContentView());
         }
+
+        if (AppBannerManager.isEnabled() && mAppBannerManager == null) {
+            mAppBannerManager = new AppBannerManager(this);
+        }
+
+        for (TabObserver observer : mObservers) observer.onContentChanged(this);
     }
 
     /**