Allow native_viewport to create new native windows on demand on Android.

shell/android/apk/src/org/chromium/mojo/shell/ViewportActivity.java

Index: shell/android/apk/src/org/chromium/mojo/shell/ViewportActivity.java
diff --git a/shell/android/apk/src/org/chromium/mojo/shell/ViewportActivity.java b/shell/android/apk/src/org/chromium/mojo/shell/ViewportActivity.java
new file mode 100644
index 0000000000000000000000000000000000000000..907fb515c1a12ec5fec52be29459072a943dffe4
--- /dev/null
+++ b/shell/android/apk/src/org/chromium/mojo/shell/ViewportActivity.java
@@ -0,0 +1,80 @@
+// Copyright 2015 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.mojo.shell;
+
+import android.app.Activity;
+import android.app.UiModeManager;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.content.res.Configuration;
+import android.os.Bundle;
+import android.util.Log;
+import android.view.WindowManager;
+
+import java.util.ArrayDeque;
+
+/**
+ * Activity for displaying on the screen from the NativeViewportService.
+ */
+public class ViewportActivity extends Activity implements ShellService.IShellBindingActivity {
+    private static final String TAG = "ViewportActivity";
+    /**
+     * Queue of ViewportActivities waiting to be attached by a PlatformViewportAndroid.
+     */
+    private static final ArrayDeque<ViewportActivity> PENDING_ACTIVITIES =
+            new ArrayDeque<ViewportActivity>();
+    private ServiceConnection mShellServiceConnection;
+
+    @Override
+    protected void onCreate(final Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        Intent serviceIntent = new Intent(this, ShellService.class);
+        startService(serviceIntent);
+        mShellServiceConnection = new ShellService.ShellServiceConnection(this);
+        bindService(serviceIntent, mShellServiceConnection, Context.BIND_AUTO_CREATE);
+
+        // TODO(tonyg): Watch activities go back to the home screen within a
+        // couple of seconds of detaching from adb. So for demonstration purposes,
+        // we just keep the screen on. Eventually we'll want a solution for
+        // allowing the screen to sleep without quitting the shell.
+        // TODO(etiennej): Verify the above is still true after the switch to a Service model.
+        UiModeManager uiModeManager = (UiModeManager) getSystemService(UI_MODE_SERVICE);
+        if (uiModeManager.getCurrentModeType() == Configuration.UI_MODE_TYPE_WATCH) {
+            getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+        }
+    }
+
+    @Override
+    public void onNewIntent(Intent intent) {
+        super.onNewIntent(intent);
+        Log.e(TAG, "Received another intent; this activity instance should only ever receive one.");

[qsr, 2015/08/06 14:13:20]

Just throws a runtime exception if this is not an intended behavior.

[etiennej, 2015/08/07 10:16:37]

Done.

+    }
+
+    @Override
+    public void onShellBound(ShellService shellService) {
+        PENDING_ACTIVITIES.add(this);
+        shellService.surfaceAvailable();
+        unbindService(mShellServiceConnection);
+    }
+
+    @Override
+    public void onShellUnbound() {
+        mShellServiceConnection = null;
+    }
+
+    public static ViewportActivity getNextUnattachedActivity() {
+        return PENDING_ACTIVITIES.remove();
+    }
+
+    /**
+     * @see Activity#onActivityResult(int, int, Intent)
+     */
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+        IntentReceiverRegistry.getInstance().onActivityResult(requestCode, resultCode, data);
+    }
+}