Add fancier press states for buttons.

- Add tint color, which applies 60% opacity in default state.
- Apply tint to dialer call buttons.
- Convert add, swap, and merge icons into drawables.

Bug: 14108639
Change-Id: Id9c08ccb035958e51d28255b8c13644c6c5fca73
diff --git a/InCallUI/res/drawable/btn_add.xml b/InCallUI/res/drawable/btn_add.xml
new file mode 100644
index 0000000..403fc1c
--- /dev/null
+++ b/InCallUI/res/drawable/btn_add.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  ~ Copyright (C) 2014 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
+  -->
+
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item android:drawable="@drawable/btn_background" />
+
+    <item>
+        <bitmap android:src="@drawable/ic_add_contact_holo_dark"
+            android:gravity="center"
+            android:tint="@color/selectable_icon_tint" />
+    </item>
+    
+</layer-list>
\ No newline at end of file