aw: Make repeated detachGLFunctor work

android_webview/glue/java/src/com/android/webview/chromium/DrawGLFunctor.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 com.android.webview.chromium;
 
 import android.graphics.Canvas;
 import android.view.View;
 
 import com.android.webview.chromium.WebViewDelegateFactory.WebViewDelegate;
 
 import org.chromium.content.common.CleanupReference;
 
 /**
  * Simple Java abstraction and wrapper for the native DrawGLFunctor flow.
  * An instance of this class can be constructed, bound to a single view context (i.e. AwContennts)
  * and then drawn and detached from the view tree any number of times (using requestDrawGL and
  * detach respectively). Then when finished with, it can be explicitly released by calling
  * destroy() or will clean itself up as required via finalizer / CleanupReference.
  */
 class DrawGLFunctor {
     private static final String TAG = DrawGLFunctor.class.getSimpleName();
 
     // Pointer to native side instance
     private CleanupReference mCleanupReference;
     private DestroyRunnable mDestroyRunnable;
+    private final long mNativeDrawGLFunctor;
     private WebViewDelegate mWebViewDelegate;
+    View mContainerView;
 
     public DrawGLFunctor(long viewContext, WebViewDelegate webViewDelegate) {
-        mDestroyRunnable = new DestroyRunnable(nativeCreateGLFunctor(viewContext), webViewDelegate);
+        mNativeDrawGLFunctor = nativeCreateGLFunctor(viewContext);
+        mDestroyRunnable = new DestroyRunnable(mNativeDrawGLFunctor);
         mCleanupReference = new CleanupReference(this, mDestroyRunnable);
         mWebViewDelegate = webViewDelegate;
     }
 
     public void destroy() {
         detach();
         if (mCleanupReference != null) {
             mCleanupReference.cleanupNow();
             mCleanupReference = null;
             mDestroyRunnable = null;
             mWebViewDelegate = null;
+            mContainerView = null;
         }
     }
 
     public void detach() {
-        mDestroyRunnable.detachNativeFunctor();
+        if (mWebViewDelegate != null && mContainerView != null) {
+            mWebViewDelegate.detachDrawGlFunctor(mContainerView, mNativeDrawGLFunctor);
+        }
     }
 
     public boolean requestDrawGL(Canvas canvas, View containerView, boolean waitForCompletion) {
         if (mDestroyRunnable.mNativeDrawGLFunctor == 0) {
             throw new RuntimeException("requested DrawGL on already destroyed DrawGLFunctor");
         }
 
         if (canvas != null && waitForCompletion) {
             throw new IllegalArgumentException(
                     "requested a blocking DrawGL with a not null canvas.");
         }
 
         if (!mWebViewDelegate.canInvokeDrawGlFunctor(containerView)) {
             return false;
         }
 
-        mDestroyRunnable.mContainerView = containerView;
+        mContainerView = containerView;
 
         if (canvas == null) {
             mWebViewDelegate.invokeDrawGlFunctor(
                     containerView, mDestroyRunnable.mNativeDrawGLFunctor, waitForCompletion);
             return true;
         }
 
         mWebViewDelegate.callDrawGlFunction(canvas, mDestroyRunnable.mNativeDrawGLFunctor);
         return true;
     }
 
     public static void setChromiumAwDrawGLFunction(long functionPointer) {
         nativeSetChromiumAwDrawGLFunction(functionPointer);
     }
 
     // Holds the core resources of the class, everything required to correctly cleanup.
     // IMPORTANT: this class must not hold any reference back to the outer DrawGLFunctor
     // instance, as that will defeat GC of that object.
     private static final class DestroyRunnable implements Runnable {
-        private WebViewDelegate mWebViewDelegate;
-        View mContainerView;
-        long mNativeDrawGLFunctor;
-        DestroyRunnable(long nativeDrawGLFunctor, WebViewDelegate webViewDelegate) {
+        private long mNativeDrawGLFunctor;
+        DestroyRunnable(long nativeDrawGLFunctor) {
             mNativeDrawGLFunctor = nativeDrawGLFunctor;
-            mWebViewDelegate = webViewDelegate;
+            assert mNativeDrawGLFunctor != 0;
         }
 
         // Called when the outer DrawGLFunctor instance has been GC'ed, i.e this is its finalizer.
         @Override
         public void run() {
-            detachNativeFunctor();
+            assert mNativeDrawGLFunctor != 0;
             nativeDestroyGLFunctor(mNativeDrawGLFunctor);
             mNativeDrawGLFunctor = 0;
         }
-
-        void detachNativeFunctor() {
-            if (mNativeDrawGLFunctor != 0 && mContainerView != null && mWebViewDelegate != null) {
-                mWebViewDelegate.detachDrawGlFunctor(mContainerView, mNativeDrawGLFunctor);
-            }
-            mContainerView = null;
-            mWebViewDelegate = null;
-        }
     }
 
     private static native long nativeCreateGLFunctor(long viewContext);
     private static native void nativeDestroyGLFunctor(long functor);
     private static native void nativeSetChromiumAwDrawGLFunction(long functionPointer);
 }