Add skeleton of content shell for android.

content/shell/android/java/org/chromium/content_shell/ContentShellActivity.java

+// Copyright (c) 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.content_shell;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.util.Log;
+
+/**
+ * This is the main activity for content_shell on android, gets invoked when the
+ * app is invoked from the launcher. This activity hosts the main UI for content
+ * shell and displays the web content via its child views.
+ */
+public class ContentShellActivity extends Activity {
+    private final String TAG = "ContentShellActivity";
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        Log.i(TAG, "Content shell started");
+    }
+}