[WebView] Add unique visual state request ids.

android_webview/java/src/org/chromium/android_webview/AwContents.java

 // Copyright 2012 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.android_webview;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.ComponentCallbacks2;
 import android.content.Context;
@@ skipping 165 matching lines @@
         }
 
         public AwScrollOffsetManager createScrollOffsetManager(
                 AwScrollOffsetManager.Delegate delegate, OverScroller overScroller) {
             return new AwScrollOffsetManager(delegate, overScroller);
         }
     }
 
     /**
      * Callback used when flushing the visual state, see {@link #flushVisualState}.
+     *
+     * <p>The {@code requestId} is the unique request id returned by
+     * {@link AwContents#flushVisualState} which can be used to match callbacks with requests.
      */
     @VisibleForTesting
     public abstract static class VisualStateFlushCallback {
-        public abstract void onComplete();
-        public abstract void onFailure();
+        public abstract void onComplete(long requestId);
+        public abstract void onFailure(long requestId);
     }
 
+    private static long sNextVisualStateRequestId = 1;
+
     private long mNativeAwContents;
     private final AwBrowserContext mBrowserContext;
     private ViewGroup mContainerView;
     private final AwLayoutChangeListener mLayoutChangeListener;
     private final Context mContext;
     private ContentViewCore mContentViewCore;
     private WindowAndroid mWindowAndroid;
     private WebContents mWebContents;
     private NavigationController mNavigationController;
     private final AwContentsClient mContentsClient;
@@ skipping 1839 matching lines @@
     /**
      * Flush the visual state.
      *
      * Flushing the visual state means queuing a callback in Blink that will be invoked when the
      * contents of the DOM tree at the moment that the callback was enqueued (or later) are drawn
      * into the screen. In other words, the following events need to happen before the callback is
      * invoked:
      * 1. The DOM tree is committed becoming the pending tree - see ThreadProxy::BeginMainFrame
      * 2. The pending tree is activated becoming the active tree
      * 3. A frame swap happens that draws the active tree into the screen
+     *
+     * @return an unique id that identifies this request. It can be used to match this request
+     * to the corresponding callback to allow reuse of {@link VisualStateFlushCallback} objects.
      */
-    public void flushVisualState(VisualStateFlushCallback callback) {
-        nativeFlushVisualState(mNativeAwContents, callback);
+    public long flushVisualState(VisualStateFlushCallback callback) {
+        long requestId = sNextVisualStateRequestId++;
+        nativeFlushVisualState(mNativeAwContents, callback, requestId);
+        return requestId;
     }
 
     //--------------------------------------------------------------------------------------------
     //  Methods called from native via JNI
     //--------------------------------------------------------------------------------------------
 
     @CalledByNative
     private static void onDocumentHasImagesResponse(boolean result, Message message) {
         message.arg1 = result ? 1 : 0;
         message.sendToTarget();
@@ skipping 92 matching lines @@
         mContentsClient.getCallbackHelper().postOnNewPicture(mPictureListenerContentProvider);
     }
 
     /**
      * Invokes the given {@link VisualStateFlushCallback}.
      *
      * @param result true if the flush request was successful and false otherwise
      */
     @CalledByNative
     public void flushVisualStateCallback(
-            final VisualStateFlushCallback callback, final boolean result) {
+            final VisualStateFlushCallback callback, final long requestId, final boolean result) {
         // Posting avoids invoking the callback inside invoking_composite_
         // (see synchronous_compositor_impl.cc and crbug/452530).
         mContainerView.getHandler().post(new Runnable() {
             @Override
             public void run() {
                 if (result) {
-                    callback.onComplete();
+                    callback.onComplete(requestId);
                 } else {
-                    callback.onFailure();
+                    callback.onFailure(requestId);
                 }
             }
         });
     }
 
     // Called as a result of nativeUpdateLastHitTestData.
     @CalledByNative
     private void updateHitTestData(
             int type, String extra, String href, String anchorText, String imgSrc) {
         mPossiblyStaleHitTestData.hitTestResultType = type;
@@ skipping 542 matching lines @@
     private native boolean nativeRestoreFromOpaqueState(long nativeAwContents, byte[] state);
 
     private native long nativeReleasePopupAwContents(long nativeAwContents);
     private native void nativeFocusFirstNode(long nativeAwContents);
     private native void nativeSetBackgroundColor(long nativeAwContents, int color);
 
     private native long nativeGetAwDrawGLViewContext(long nativeAwContents);
     private native long nativeCapturePicture(long nativeAwContents, int width, int height);
     private native void nativeEnableOnNewPicture(long nativeAwContents, boolean enabled);
     private native void nativeFlushVisualState(
-            long nativeAwContents, VisualStateFlushCallback callback);
+            long nativeAwContents, VisualStateFlushCallback callback, long requestId);
     private native void nativeClearView(long nativeAwContents);
     private native void nativeSetExtraHeadersForUrl(long nativeAwContents,
             String url, String extraHeaders);
 
     private native void nativeInvokeGeolocationCallback(
             long nativeAwContents, boolean value, String requestingFrame);
 
     private native void nativeSetJsOnlineProperty(long nativeAwContents, boolean networkUp);
 
     private native void nativeTrimMemory(long nativeAwContents, int level, boolean visible);
 
     private native void nativeCreatePdfExporter(long nativeAwContents, AwPdfExporter awPdfExporter);
 
     private native void nativePreauthorizePermission(long nativeAwContents, String origin,
             long resources);
 
     private native void nativePostMessageToFrame(long nativeAwContents, String frameId,
             String message, String sourceOrigin, String targetOrigin, int[] msgPorts);
 
     private native void nativeCreateMessageChannel(long nativeAwContents,
             ValueCallback<MessagePort[]> callback);
 }