Move utility classes in a separate static target

Split up utility classes that can be re-used in other IComposer related
tests (such as the IVrComposerClient tests).

Changes:
 * Move GraphicsComposerCallback into separate module
 * Extract TestCommandReader in separate module
 * Extract Composer::execute() from test class

Bug: 38203529
Test: Compiled
Change-Id: I0d1193469e9dd94c477a63058f98111c162dfa99
diff --git a/graphics/composer/2.1/vts/functional/TestCommandReader.h b/graphics/composer/2.1/vts/functional/TestCommandReader.h
new file mode 100644
index 0000000..657a463
--- /dev/null
+++ b/graphics/composer/2.1/vts/functional/TestCommandReader.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#ifndef TEST_COMMAND_READER_H
+#define TEST_COMMAND_READER_H
+
+#include <IComposerCommandBuffer.h>
+
+namespace android {
+namespace hardware {
+namespace graphics {
+namespace composer {
+namespace V2_1 {
+namespace tests {
+
+// A command parser that checks that no error nor unexpected commands are
+// returned.
+class TestCommandReader : public CommandReaderBase {
+ public:
+  // Parse all commands in the return command queue.  Call GTEST_FAIL() for
+  // unexpected errors or commands.
+  void parse();
+};
+
+}  // namespace tests
+}  // namespace V2_1
+}  // namespace composer
+}  // namespace graphics
+}  // namespace hardware
+}  // namespace android
+
+#endif  // TEST_COMMAND_READER_H