New test player stub to load mock native players.

Added a new class TestPlayerStub that takes a magic url in the setDataSource call.
Based on the value of the url, the stub is going to load a DL and create the concrete
player used during the test.
After these initialization steps TestPlayerStub is just a wrapper.

Added a new functional test MediaPlayerInvokeTest to demonstrate how a new
mock player to test the invoke method can be loaded.

Added a new mock player for the invoke test: invoke_mock_media_player.cpp.
diff --git a/media/tests/players/Android.mk b/media/tests/players/Android.mk
new file mode 100644
index 0000000..eb50a51
--- /dev/null
+++ b/media/tests/players/Android.mk
@@ -0,0 +1,29 @@
+# Copyright (C) 2009 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= invoke_mock_media_player.cpp
+
+LOCAL_SHARED_LIBRARIES:= \
+    libbinder \
+    libutils
+
+LOCAL_MODULE:= invoke_mock_media_player
+LOCAL_MODULE_TAGS := test eng
+LOCAL_PRELINK_MODULE:= false
+
+include $(BUILD_SHARED_LIBRARY)