AndroidOverlay implementation using Dialog.

content/public/android/java/src/org/chromium/content/browser/androidoverlay/DialogOverlayImpl.java

+// Copyright 2017 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.content.browser.androidoverlay;
+
+import android.content.Context;
+import android.os.Handler;
+import android.os.IBinder;
+import android.view.Surface;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.gfx.mojom.Rect;
+import org.chromium.media.mojom.AndroidOverlay;
+import org.chromium.media.mojom.AndroidOverlayClient;
+import org.chromium.media.mojom.AndroidOverlayConfig;
+import org.chromium.mojo.system.MojoException;
+
+/**
+ * Default AndroidOverlay impl.  Uses a separate (shared) overlay thread to own a Dialog instance,
+ * probably via a separate object that operates only on that thread.  We will post messages to /
+ * from that thread from the UI thread.
+ */
+@JNINamespace("content")
+public class DialogOverlayImpl implements AndroidOverlay, DialogOverlayCore.Host {
+    private static final String TAG = "DialogOverlayImpl";
+
+    private AndroidOverlayClient mClient;
+    private Handler mOverlayHandler;
+    // Runnable that we'll run when the overlay notifies us that it's been released.
+    private Runnable mReleasedRunnable;
+
+    private final ThreadHoppingHost mHoppingHost;
+
+    private DialogOverlayCore mDialogCore;
+
+    private long mNativeHandle;
+
+    // If nonzero, then we have registered a surface with this ID.
+    private int mSurfaceId;
+
+    /**
+     * @param client Mojo client interface.
+     * @param config initial overlay configuration.
+     * @param handler handler that posts to the overlay thread.  This is the android UI thread that
+     * the dialog uses, not the browser UI thread.
+     * @param provider the overlay provider that owns us.
+     */
+    public DialogOverlayImpl(AndroidOverlayClient client, final AndroidOverlayConfig config,
+            Handler overlayHandler, Runnable releasedRunnable) {
+        ThreadUtils.assertOnUiThread();
+
+        mClient = client;
+        mReleasedRunnable = releasedRunnable;
+        mOverlayHandler = overlayHandler;
+
+        mDialogCore = new DialogOverlayCore();
+        mHoppingHost = new ThreadHoppingHost(this);
+
+        // Post init to the overlay thread.
+        final DialogOverlayCore dialogCore = mDialogCore;
+        final Context context = ContextUtils.getApplicationContext();
+        mOverlayHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                dialogCore.initialize(context, config, mHoppingHost);
+            }
+        });
+
+        // Register to get token updates.
+        mNativeHandle = nativeRegisterForTokens(config.routingToken.high, config.routingToken.low);
+        assert mNativeHandle != 0;
+    }
+
+    // AndroidOverlay impl.
+    // Client is done with this overlay.
+    @Override
+    public void close() {
+        ThreadUtils.assertOnUiThread();
+
+        // TODO(liberato): verify that this actually works, else add an explicit shutdown and hope
+        // that the client calls it.
+
+        // Allow surfaceDestroyed to proceed, if it's waiting.
+        mHoppingHost.onCleanup();
+
+        // Notify |mDialogCore| that it has been released.  This might not be called if it notifies
+        // us that it's been destroyed.  We still might send it in that case if the client closes
+        // the connection before we find out that it's been destroyed on the overlay thread.
+        if (mDialogCore != null) {
+            final DialogOverlayCore dialogCore = mDialogCore;
+            mOverlayHandler.post(new Runnable() {
+                @Override
+                public void run() {
+                    dialogCore.release();
+                }
+            });
+
+            // Note that we might get messagaes from |mDialogCore| after this, since they might be
+            // dispatched before |r| arrives.  Clearing |mDialogCore| causes us to ignore them.
+            cleanup();
+        }
+
+        // Notify the provider that we've been released by the client.  Note that the surface might
+        // not have been destroyed yet, but that's okay.  We could wait for a callback from the
+        // dialog core before proceeding, but this makes it easier for the client to destroy and
+        // re-create an overlay without worrying about an intermittent failure due to having too
+        // many overlays open at once.
+        mReleasedRunnable.run();
+    }
+
+    // AndroidOverlay impl.
+    @Override
+    public void onConnectionError(MojoException e) {
+        ThreadUtils.assertOnUiThread();
+
+        close();
+    }
+
+    // AndroidOverlay impl.
+    @Override
+    public void scheduleLayout(final Rect rect) {
+        ThreadUtils.assertOnUiThread();
+
+        if (mDialogCore == null) return;
+
+        final DialogOverlayCore dialogCore = mDialogCore;
+        mOverlayHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                dialogCore.layoutSurface(rect);
+            }
+        });
+    }
+
+    // DialogOverlayCore.Host impl.
+    // |surface| is now ready.  Register it with the surface tracker, and notify the client.
+    @Override
+    public void onSurfaceReady(Surface surface) {
+        ThreadUtils.assertOnUiThread();
+
+        if (mDialogCore == null || mClient == null) return;
+
+        mSurfaceId = nativeRegisterSurface(surface);
+        mClient.onSurfaceReady(mSurfaceId);
+    }
+
+    // DialogOverlayCore.Host impl.
+    @Override
+    public void onOverlayDestroyed() {
+        ThreadUtils.assertOnUiThread();
+
+        if (mDialogCore == null) return;
+
+        // Notify the client that the overlay is gone.
+        if (mClient != null) mClient.onDestroyed();
+
+        // Also clear out |mDialogCore| to prevent us from sending useless messages to it.  Note
+        // that we might have already sent useless messages to it, and it should be robust against
+        // that sort of thing.
+        cleanup();
+
+        // Note that we don't notify |mReleasedRunnable| yet, though we could.  We wait for the
+        // client to close their connection first.
+    }
+
+    // DialogOverlayCore.Host impl.
+    // Due to threading issues, |mHoppingHost| doesn't forward this.
+    @Override
+    public void waitForCleanup() {
+        assert false : "Not reached";
+    }
+
+    /**
+     * Send |token| to the |mDialogCore| on the overlay thread.
+     */
+    private void sendWindowTokenToCore(final IBinder token) {
+        ThreadUtils.assertOnUiThread();
+
+        final DialogOverlayCore dialogCore = mDialogCore;
+        mOverlayHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                dialogCore.onWindowToken(token);
+            }
+        });
+    }
+
+    /**
+     * Callback from native that the window token has changed.
+     */
+    @CalledByNative
+    public void onWindowToken(final IBinder token) {
+        ThreadUtils.assertOnUiThread();
+
+        if (mDialogCore == null) return;
+
+        // Forward this change.
+        // Note that if we don't have a window token, then we could wait until we do, simply by
+        // skipping sending null if we haven't sent any non-null token yet.  If we're transitioning
+        // between windows, that might make the client's job easier. It wouldn't have to guess when
+        // a new token is available.
+        sendWindowTokenToCore(token);
+    }
+
+    /**
+     * Callback from native that we will be getting no additional tokens.
+     */
+    @CalledByNative
+    public void onDismissed() {
+        ThreadUtils.assertOnUiThread();
+
+        // Notify the client that the overlay is going away.
+        if (mClient != null) mClient.onDestroyed();
+
+        // Notify |mDialogCore| that it lost the token, if it had one.
+        sendWindowTokenToCore(null);
+
+        cleanup();
+    }
+
+    /**
+     * Unregister for callbacks, unregister any surface that we have, and forget about
+     * |mDialogCore|.  Multiple calls are okay.
+     */
+    private void cleanup() {
+        ThreadUtils.assertOnUiThread();
+
+        if (mSurfaceId != 0) {
+            nativeUnregisterSurface(mSurfaceId);
+            mSurfaceId = 0;
+        }
+
+        // Note that we might not be registered for a token.
+        if (mNativeHandle != 0) {
+            nativeUnregisterForTokens(mNativeHandle);
+            mNativeHandle = 0;
+        }
+
+        // Also clear out |mDialogCore| to prevent us from sending useless messages to it.  Note
+        // that we might have already sent useless messages to it, and it should be robust against
+        // that sort of thing.
+        mDialogCore = null;
+
+        // If we wanted to send any message to |mClient|, we should have done so already.
+        mClient = null;
+    }
+
+    /**
+     * Initializes native side.  Will register for onWindowToken callbacks on |this|.  Returns a
+     * handle that should be provided to nativeUnregisterForTokens.
+     */
+    private native long nativeRegisterForTokens(long high, long low);

[boliu, 2017/04/26 00:19:08]

maybe should rename these to make it should like java-native pair, so can be
named nativeInit

[liberato (no reviews please), 2017/04/26 17:26:35]

Done.

+
+    /**
+     * Stops native side and deallocates |handle|.
+     */
+    private static native void nativeUnregisterForTokens(long handle);

[boliu, 2017/04/26 00:19:08]

if you name the parameter "long nativeDialogOverlayImpl", then the generated jni
binding will call the an instance method on the native DialogOverlayImpl. then
this can probably just renamed nativeDestroy

[liberato (no reviews please), 2017/04/26 17:26:35]

Done.

+
+    /**
+     * Register a surface and return the surface id for it.
+     * @param surface Surface that we should register.
+     * @return surface id that we associated with |surface|.
+     */
+    private static native int nativeRegisterSurface(Surface surface);
+
+    /**
+     * Unregister a surface.
+     * @param surfaceId Id that was returned by registerSurface.
+     */
+    private static native void nativeUnregisterSurface(int surfaceId);
+}