Add @TargetApi to version dependent methods.

chrome/android/java/src/org/chromium/chrome/browser/multiwindow/MultiWindowUtils.java

 // 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.
 
 package org.chromium.chrome.browser.multiwindow;
 
 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.ActivityManager;
 import android.app.ActivityManager.AppTask;
@@ skipping 224 matching lines @@
         // 6. Default to regular ChromeTabbedActivity.
         return ChromeTabbedActivity.class;
     }
 
     /**
      * @param className The class name of the Activity to look for in Android recents
      * @param context The current Context, used to retrieve the ActivityManager system service.
      * @return True if the Activity still has a task in Android recents, regardless of whether
      *         the Activity has been destroyed.
      */
+    @TargetApi(Build.VERSION_CODES.M)

[Maria, 2016/08/05 23:42:06]

I think this would work with L and above

[estevenson, 2016/08/08 14:23:49]

Same as ChromeTabbedActivity, it looks like
ActivityManager.RecentTaskInfo.baseActivity was added in M
https://developer.android.com/reference/android/app/ActivityManager.RecentTas....

     private boolean isActivityTaskInRecents(String className, Context context) {
         ActivityManager activityManager = (ActivityManager)
                 context.getSystemService(Context.ACTIVITY_SERVICE);
         List<AppTask> appTasks = activityManager.getAppTasks();
         for (AppTask task : appTasks) {
             if (task.getTaskInfo() == null || task.getTaskInfo().baseActivity == null) continue;
             String baseActivity = task.getTaskInfo().baseActivity.getClassName();
             if (TextUtils.equals(baseActivity, className)) return true;
         }
         return false;
@@ skipping 41 matching lines @@
         if (isLegacyMultiWindow(activity)) {
             if (TextUtils.equals(ChromeTabbedActivity.class.getName(),
                     intent.getComponent().getClassName())) {
                 intent.setClassName(activity, MultiInstanceChromeTabbedActivity.class.getName());
             }
             intent.setFlags(intent.getFlags()
                     & ~(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_NEW_DOCUMENT));
         }
     }
 }