[Remoting Android] Make JniClient own JniDisplayHandler

remoting/android/java/src/org/chromium/chromoting/jni/Display.java

 // Copyright 2016 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.chromoting.jni;
 
 import android.graphics.Bitmap;
 import android.graphics.Point;
 import android.os.Looper;
 
@@ skipping 33 matching lines @@
 
     /** Bitmap holding a copy of the latest video frame. Accessed on the UI and graphics threads. */
     private Bitmap mFrameBitmap;
 
     /** Position of cursor hot-spot. Accessed on the graphics thread. */
     private Point mCursorHotspot = new Point();
 
     /** Bitmap holding the cursor shape. Accessed on the graphics thread. */
     private Bitmap mCursorBitmap;
 
-    public Display() {
-        mNativeJniDisplayHandler = nativeInit();
+    private Display(long nativeDisplayHandler) {
+        mNativeJniDisplayHandler = nativeDisplayHandler;
     }
 
     /**
      * @return the pointer to the native C++ object.
      */
     public long getNativePointer() {
         return mNativeJniDisplayHandler;
     }
 
     /**
      * Sets the redraw callback to the provided functor. Provide a value of null whenever the
      * window is no longer visible so that we don't continue to draw onto it. Called on the UI
      * thread.
      */
     public void provideRedrawCallback(Runnable redrawCallback) {
         synchronized (mRedrawCallbackLock) {
             mRedrawCallback = redrawCallback;
         }
     }
 
     /**
-     * Destroys its resources and the native counterpart. Called on the UI thread.
+     * Invalidates this object and disconnects from the native display handler. Called on the
+     * display thread by the native code.
      */
-    public void destroy() {
+    @CalledByNative
+    private void invalidate() {
         // Drop the reference to free the Bitmap for GC.
         synchronized (mFrameLock) {
             mFrameBitmap = null;
         }
 
         provideRedrawCallback(null);
-        nativeDestroy(mNativeJniDisplayHandler);
         mNativeJniDisplayHandler = 0;
     }
 
     /** Forces the native graphics thread to redraw to the canvas. Called on the UI thread. */
     public boolean redrawGraphics() {
         if (mRedrawCallback == null) return false;
 
         nativeScheduleRedraw(mNativeJniDisplayHandler);
         return true;
     }
@@ skipping 67 matching lines @@
     /** Position of cursor hotspot within cursor image. Called on the graphics thread. */
     public Point getCursorHotspot() {
         return mCursorHotspot;
     }
 
     /** Returns the current cursor shape. Called on the graphics thread. */
     public Bitmap getCursorBitmap() {
         return mCursorBitmap;
     }
 
-    private native long nativeInit();
-
-    private native void nativeDestroy(long nativeJniDisplayHandler);
+    @CalledByNative
+    private static Display createJavaDisplayObject(long nativeDisplayHandler) {
+        return new Display(nativeDisplayHandler);
+    }
 
     /** Schedules a redraw on the native graphics thread. */
     private native void nativeScheduleRedraw(long nativeJniDisplayHandler);
 }