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.app.Dialog;
+import android.content.Context;
+import android.os.IBinder;
+import android.view.Surface;
+import android.view.Window;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.ThreadUtils;
+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 main thread.
+ */
+public class DialogOverlayImpl implements AndroidOverlay, DialogOverlayCore.Host,
+                                          DialogOverlayOperations.WindowTokenListener {
+    private static final String TAG = "DialogOverlayImpl";
+
+    private final DialogOverlayOperations mOps;
+    private final ThreadHoppingHost mHoppingHost;
+    private AndroidOverlayClient mClient;
+    private DialogOverlayCore mDialogCore;
+
+    // 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,
+            DialogOverlayOperations ops) {
+        ThreadUtils.assertOnUiThread();
+
+        mClient = client;
+        mOps = ops;
+        mDialogCore = new DialogOverlayCore();
+        mHoppingHost = new ThreadHoppingHost(this);
+
+        // Post init to the overlay thread.
+        final DialogOverlayCore dialogCore = mDialogCore;
+        final Context context = ContextUtils.getApplicationContext();
+        mOps.getOverlayHandler().post(new Runnable() {
+            @Override
+            public void run() {
+                // Create the dialog, but don't lay it out or show it yet.  |dialogCore| will do
+                // that when we get a window token.
+                Dialog dialog = new Dialog(context, android.R.style.Theme_NoDisplay);

[boliu, 2017/04/22 00:22:43]

do this stuff in dialogcore? seems odd this is here

[liberato (no reviews please), 2017/04/24 22:19:41]

it was originally to allow DialogOverlayCoreTest to inject its own dialogs. 
however, i think that it's no longer needed.  i'll merge it back.

+                dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
+                dialog.setCancelable(false);
+                dialogCore.initialize(dialog, config, mHoppingHost);
+            }
+        });
+
+        // Register to get token updates.
+        mOps.registerWindowTokenListener(config.routingToken, this);
+    }
+
+    @Override
+    public void onSurfaceReady(Surface surface) {
+        ThreadUtils.assertOnUiThread();
+
+        if (mDialogCore == null || mClient == null) return;
+
+        mSurfaceId = mOps.registerSurface(surface);
+        mClient.onSurfaceReady(mSurfaceId);
+    }
+
+    @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 |mOps| yet, though we could.  We wait for the client to close
+        // their connection first.
+    }
+
+    // Due to threading issues, |mHoppingHost| doesn't forward this.
+    @Override
+    public void waitForCleanup() {
+        assert false : "Not reached";
+    }
+
+    // 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;
+            mOps.getOverlayHandler().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.
+        mOps.notifyReleased();
+    }
+
+    private void sendWindowTokenToCore(final IBinder token) {
+        ThreadUtils.assertOnUiThread();
+
+        final DialogOverlayCore dialogCore = mDialogCore;
+        mOps.getOverlayHandler().post(new Runnable() {
+            @Override
+            public void run() {
+                dialogCore.onWindowToken(token);
+            }
+        });
+    }
+
+    @Override
+    public void onWindowToken(final IBinder token) {

[boliu, 2017/04/22 00:22:43]

this class is implementing three interfaces, and it's really hard to keep track
of which method is from which interface. maybe make Host/Listener inner classes?
although at some point you have to wonder if all of these classes are actually
worth it..

at minimum add comments and group methods from same interface together

[liberato (no reviews please), 2017/04/24 22:19:42]

i've merged Ops, so WindowTokenListener is gone now.

Host: already an inner class of DialogOverlayCore for the junit test.

+        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);
+    }
+
+    @Override
+    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();
+    }
+
+    @Override
+    public void onConnectionError(MojoException e) {
+        ThreadUtils.assertOnUiThread();
+
+        close();
+    }
+
+    @Override
+    public void scheduleLayout(final Rect rect) {
+        ThreadUtils.assertOnUiThread();
+
+        if (mDialogCore == null) return;
+
+        final DialogOverlayCore dialogCore = mDialogCore;
+        mOps.getOverlayHandler().post(new Runnable() {
+            @Override
+            public void run() {
+                dialogCore.layoutSurface(rect);
+            }
+        });
+    }
+
+    /**
+     * 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) {
+            mOps.unregisterSurface(mSurfaceId);
+            mSurfaceId = 0;
+        }
+
+        // Note that we might not be registered for a token.
+        mOps.unregisterWindowTokenListenerIfNeeded();
+
+        // 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;
+    }
+}