Add integration tests for WebAPKs

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
index 360b52624cac92b4f4021ac8f1d2fbdeca45270c..5d78b491c962ebcaa752d04fbbdb49554221b2f7 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
@@ -169,8 +169,10 @@ public class WebApkActivity extends WebappActivity {
     public void onDeferredStartup() {
         super.onDeferredStartup();
 
-        mUpdateManager = new WebApkUpdateManager(this);
-        mUpdateManager.updateIfNeeded(getActivityTab(), (WebApkInfo) mWebappInfo);
+        mUpdateManager = createUpdateManager();
+        if (mUpdateManager != null) {
+            mUpdateManager.updateIfNeeded(getActivityTab(), (WebApkInfo) mWebappInfo);
+        }
     }
 
     @Override
@@ -204,4 +206,9 @@ public class WebApkActivity extends WebappActivity {
         }
         super.onDestroyInternal();
     }
+
+    /* Creates WebApkUpdateManager. In its own function for the sake of tests. */
+    protected WebApkUpdateManager createUpdateManager() {
+        return new WebApkUpdateManager(this);
+    }
 }