[Composer] Create place holder for Composer 2.4.

Create place holder for composer 2.4.

Minor: Extend DisplayCapability to include protected contents.

BUG: 135929065
Test: build
Change-Id: I9dbdb21f4a69027bedd95cd54e9c3c652bbe9006
diff --git a/graphics/composer/2.4/IComposerClient.hal b/graphics/composer/2.4/IComposerClient.hal
new file mode 100644
index 0000000..8fe0976
--- /dev/null
+++ b/graphics/composer/2.4/IComposerClient.hal
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2019 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.
+ */
+
+package android.hardware.graphics.composer@2.4;
+
+import @2.1::Display;
+import @2.1::Error;
+import @2.3::IComposerClient;
+
+interface IComposerClient extends @2.3::IComposerClient {
+
+    /**
+     * Required capabilities which are supported by the display. The
+     * particular set of supported capabilities for a given display may be
+     * retrieved using getDisplayCapabilities.
+     */
+    enum DisplayCapability : uint32_t {
+        /**
+         * Indicates that the display supports protected contents.
+         * When returned, hardware composer must be able to accept client target
+         * with protected buffers.
+         */
+        PROTECTED_CONTENTS = 4,
+    };
+
+    /**
+     * Provides a list of supported capabilities (as described in the
+     * definition of DisplayCapability above). This list must not change after
+     * initialization.
+     *
+     * @return error is NONE upon success. Otherwise,
+     *     BAD_DISPLAY when an invalid display handle was passed in.
+     * @return capabilities is a list of supported capabilities.
+     */
+    getDisplayCapabilities_2_4(Display display)
+              generates (Error error,
+                         vec<DisplayCapability> capabilities);
+};