Refactor handleMessage() functionality in fullscreen

chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java

 // Copyright 2014 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.fullscreen;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ObjectAnimator;
 import android.app.Activity;
@@ skipping 17 matching lines @@
 import org.chromium.base.ApplicationStatus.ActivityStateListener;
 import org.chromium.base.BaseChromiumApplication;
 import org.chromium.base.BaseChromiumApplication.WindowFocusChangedListener;
 import org.chromium.base.TraceEvent;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.Tab;
 import org.chromium.chrome.browser.fullscreen.FullscreenHtmlApiHandler.FullscreenHtmlApiDelegate;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 import org.chromium.content.browser.ContentViewCore;
 
+import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.HashSet;
 
 /**
  * A class that manages control and content views to create the fullscreen mode.
  */
 public class ChromeFullscreenManager
         extends FullscreenManager implements ActivityStateListener, WindowFocusChangedListener {
     // Minimum showtime of the toolbar (in ms).
     private static final long MINIMUM_SHOW_DURATION_MS = 3000;
@@ skipping 94 matching lines @@
             if (mControlContainer.getVisibility() == visibility) return;
             // requestLayout is required to trigger a new gatherTransparentRegion(), which
             // only occurs together with a layout and let's SurfaceFlinger trim overlays.
             // This may be almost equivalent to using View.GONE, but we still use View.INVISIBLE
             // since drawing caches etc. won't be destroyed, and the layout may be less expensive.
             mControlContainer.setVisibility(visibility);
             mControlContainer.requestLayout();
         }
     };
 
+    // This static inner class holds a WeakReference to the outer object, to avoid triggering the
+    // lint HandlerLeak warning.
+    private static class FullscreenHandler extends Handler {
+        private final WeakReference<ChromeFullscreenManager> mChromeFullscreenManager;
+
+        public FullscreenHandler(ChromeFullscreenManager chromeFullscreenManager) {
+            mChromeFullscreenManager = new WeakReference<ChromeFullscreenManager>(
+                    chromeFullscreenManager);
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            if (msg == null) return;
+            ChromeFullscreenManager chromeFullscreenManager = mChromeFullscreenManager.get();
+            if (chromeFullscreenManager == null) return;
+            switch (msg.what) {
+                case MSG_ID_CONTROLS_REQUEST_LAYOUT:
+                    chromeFullscreenManager.mControlContainer.requestLayout();
+                    break;
+                case MSG_ID_HIDE_CONTROLS:
+                    chromeFullscreenManager.update(false);
+                    break;
+                default:
+                    assert false : "Unexpected message for ID: " + msg.what;
+                    break;
+            }
+        }
+    }
+
     /**
      * Creates an instance of the fullscreen mode manager.
      * @param activity The activity that supports fullscreen.
      * @param controlContainer Container holding the controls (Toolbar).
      * @param enabled Whether fullscreen is globally enabled.
      * @param modelSelector The model selector providing access to the current tab.
      */
     public ChromeFullscreenManager(Activity activity, View controlContainer, boolean enabled,
             boolean persistentFullscreenSupported, TabModelSelector modelSelector,
             int resControlContainerHeight) {
         super(activity.getWindow(), modelSelector, enabled, persistentFullscreenSupported);
 
         mActivity = activity;
         ApplicationStatus.registerStateListenerForActivity(this, activity);
         ((BaseChromiumApplication) activity.getApplication())
                 .registerWindowFocusChangedListener(this);
 
         mWindow = activity.getWindow();
-        mHandler = new Handler() {
-            @Override
-            public void handleMessage(Message msg) {
-                if (msg == null) return;
-                switch (msg.what) {
-                    case MSG_ID_CONTROLS_REQUEST_LAYOUT:
-                        mControlContainer.requestLayout();
-                        break;
-                    case MSG_ID_HIDE_CONTROLS:
-                        update(false);
-                        break;
-                    default:
-                        assert false : "Unexpected message for ID: " + msg.what;
-                        break;
-                }
-            }
-        };
+        mHandler = new FullscreenHandler(this);
         setControlContainer(controlContainer);
         Resources resources = mWindow.getContext().getResources();
         mControlContainerHeight = resources.getDimensionPixelSize(resControlContainerHeight);
         mRendererContentOffset = mControlContainerHeight;
         mEnabled = enabled;
         updateControlOffset();
     }
 
     /**
      * @return Whether or not fullscreen is enabled.
@@ skipping 526 matching lines @@
         mControlAnimation.start();
         mCurrentAnimationIsShowing = show;
     }
 
     @Override
     public void onContentViewScrollingStateChanged(boolean scrolling) {
         mContentViewScrolling = scrolling;
         if (!scrolling) updateVisuals();
     }
 }