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 org.chromium.base.ContextUtils;
+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-ui 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 AndroidOverlayClient mClient;

[boliu, 2017/03/30 22:42:02]

any/all of this can be final?

[liberato (no reviews please), 2017/04/04 17:49:29]

client, dialogcore: no, cleared when they're cleaned up.
ops, host: done.

+    private DialogOverlayOperations mOps;
+    private DialogOverlayCore mDialogCore;
+    private ThreadHoppingHost mHoppingHost;
+
+    // If nonzero, then we have registered a surface with this ID.
+    private int mSurfaceId;
+
+    // Are we currently registered with |mOps| to receive token updates?
+    private boolean mRegisteredForToken;
+
+    /**
+     * @param client Mojo client interface.
+     * @param config initial overlay configuration.
+     * @param handler handler that posts to the overlay-ui 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) {
+        mClient = client;

[boliu, 2017/03/30 22:42:03]

probably worth asserting what thread each method runs on, more for documentation
than anything else

[liberato (no reviews please), 2017/04/04 17:49:29]

Done.

+        mOps = ops;
+        mDialogCore = new DialogOverlayCore();
+        mHoppingHost = new ThreadHoppingHost(this);
+
+        // Post init to the proper (overlay-ui) thread.
+        final DialogOverlayCore dialogCore = mDialogCore;
+        final Context context = ContextUtils.getApplicationContext();
+        mOps.getOverlayUiHandler().post(new Runnable() {
+            @Override
+            public void run() {
+                Dialog dialog = mOps.createDialog(context);
+                dialogCore.initialize(dialog, config, mHoppingHost);
+            }
+        });
+
+        // Register to get token updates.
+        mOps.registerWindowTokenListener(config.routingToken, this);
+        mRegisteredForToken = true;
+    }
+
+    @Override
+    public void onSurfaceReady(Surface surface) {
+        if (mDialogCore == null || mClient == null) return;
+
+        mSurfaceId = mOps.registerSurface(surface);
+        mClient.onSurfaceReady(mSurfaceId);
+    }
+
+    @Override
+    public void onOverlayDestroyed() {
+        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() {
+        // 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-ui thread.
+        if (mDialogCore != null) {
+            final DialogOverlayCore dialogCore = mDialogCore;
+            mOps.getOverlayUiHandler().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) {
+        final DialogOverlayCore dialogCore = mDialogCore;
+        mOps.getOverlayUiHandler().post(new Runnable() {
+            @Override
+            public void run() {
+                dialogCore.onWindowToken(token);
+            }
+        });
+    }
+
+    @Override
+    public void onWindowToken(final IBinder token) {
+        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() {
+        // 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) {
+        close();
+    }
+
+    @Override
+    public void scheduleLayout(final Rect rect) {
+        if (mDialogCore == null) return;
+
+        final DialogOverlayCore dialogCore = mDialogCore;
+        mOps.getOverlayUiHandler().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() {
+        if (mSurfaceId != 0) {
+            mOps.unregisterSurface(mSurfaceId);
+            mSurfaceId = 0;
+        }
+
+        if (mRegisteredForToken) {
+            mOps.unregisterWindowTokenListener();
+            mRegisteredForToken = false;
+        }
+
+        // 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.
+        if (mDialogCore != null) mDialogCore = null;

[boliu, 2017/03/30 22:42:03]

redundant check

[liberato (no reviews please), 2017/04/04 17:49:29]

Done.

+
+        // If we wanted to send any message to |mClient|, we should have done so already.
+        mClient = null;
+    }
+}