diff --git a/InCallUI/res/drawable/btn_add.xml b/InCallUI/res/drawable/btn_add.xml
index 515d65b..7d5e90f 100644
--- a/InCallUI/res/drawable/btn_add.xml
+++ b/InCallUI/res/drawable/btn_add.xml
@@ -18,12 +18,13 @@
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item android:drawable="@drawable/btn_background" />
+    <item android:id="@+id/backgroundItem"
+          android:drawable="@drawable/btn_background" />
 
     <item>
         <bitmap android:src="@drawable/ic_toolbar_add_call"
             android:gravity="center"
             android:tint="@color/selectable_icon_tint" />
     </item>
-    
+
 </layer-list>
\ No newline at end of file
diff --git a/InCallUI/res/drawable/btn_change_to_video.xml b/InCallUI/res/drawable/btn_change_to_video.xml
index 962539e..a26cee3 100644
--- a/InCallUI/res/drawable/btn_change_to_video.xml
+++ b/InCallUI/res/drawable/btn_change_to_video.xml
@@ -18,7 +18,8 @@
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item android:drawable="@drawable/btn_background" />
+    <item android:id="@+id/backgroundItem"
+          android:drawable="@drawable/btn_background" />
 
     <item>
         <bitmap android:src="@drawable/ic_toolbar_video"
diff --git a/InCallUI/res/drawable/btn_change_to_voice.xml b/InCallUI/res/drawable/btn_change_to_voice.xml
index fdeae07..86a7f21 100644
--- a/InCallUI/res/drawable/btn_change_to_voice.xml
+++ b/InCallUI/res/drawable/btn_change_to_voice.xml
@@ -18,7 +18,8 @@
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item android:drawable="@drawable/btn_background" />
+    <item android:id="@+id/backgroundItem"
+          android:drawable="@drawable/btn_background" />
 
     <item>
         <bitmap android:src="@drawable/ic_toolbar_audio_phone"
diff --git a/InCallUI/res/drawable/btn_compound_background.xml b/InCallUI/res/drawable/btn_compound_background.xml
index 93e6c31..36aab0d 100644
--- a/InCallUI/res/drawable/btn_compound_background.xml
+++ b/InCallUI/res/drawable/btn_compound_background.xml
@@ -24,7 +24,7 @@
                   android:drawable="@drawable/btn_selected_focused" />
 
             <item android:state_focused="true"
-                  android:drawable="@drawable/btn_unselected_focused" />cd
+                  android:drawable="@drawable/btn_unselected_focused" />
 
             <item android:state_selected="true"
                 android:drawable="@drawable/btn_selected" />
diff --git a/InCallUI/res/drawable/btn_compound_dialpad.xml b/InCallUI/res/drawable/btn_compound_dialpad.xml
index fcd9a3c..1b78ead 100644
--- a/InCallUI/res/drawable/btn_compound_dialpad.xml
+++ b/InCallUI/res/drawable/btn_compound_dialpad.xml
@@ -18,7 +18,8 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
     <!-- The standard "compound button" background. -->
-    <item android:drawable="@drawable/btn_compound_background" />
+    <item android:id="@+id/compoundBackgroundItem"
+          android:drawable="@drawable/btn_compound_background" />
 
     <!-- ...and the actual icon on top.  Use an explicit <bitmap> to avoid scaling
          the icon up to the full size of the button. -->
diff --git a/InCallUI/res/drawable/btn_compound_hold.xml b/InCallUI/res/drawable/btn_compound_hold.xml
index dcf9507..7974efa 100644
--- a/InCallUI/res/drawable/btn_compound_hold.xml
+++ b/InCallUI/res/drawable/btn_compound_hold.xml
@@ -18,7 +18,8 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
     <!-- The standard "compound button" background. -->
-    <item android:drawable="@drawable/btn_compound_background" />
+    <item android:id="@+id/compoundBackgroundItem"
+          android:drawable="@drawable/btn_compound_background" />
 
     <!-- ...and the actual icon on top.  Use an explicit <bitmap> to avoid scaling
          the icon up to the full size of the button. -->
diff --git a/InCallUI/res/drawable/btn_compound_mute.xml b/InCallUI/res/drawable/btn_compound_mute.xml
index 68a8c9b..86708fb 100644
--- a/InCallUI/res/drawable/btn_compound_mute.xml
+++ b/InCallUI/res/drawable/btn_compound_mute.xml
@@ -18,7 +18,8 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
     <!-- The standard "compound button" background. -->
-    <item android:drawable="@drawable/btn_compound_background" />
+    <item android:id="@+id/compoundBackgroundItem"
+          android:drawable="@drawable/btn_compound_background" />
 
     <!-- Use an explicit <bitmap> to avoid scaling the icon up to the full size of the button. -->
     <item>
diff --git a/InCallUI/res/drawable/btn_compound_video_off.xml b/InCallUI/res/drawable/btn_compound_video_off.xml
index 8af4209..b942cd0 100644
--- a/InCallUI/res/drawable/btn_compound_video_off.xml
+++ b/InCallUI/res/drawable/btn_compound_video_off.xml
@@ -19,7 +19,8 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
     <!-- The standard "compound button" background. -->
-    <item android:drawable="@drawable/btn_compound_background" />
+    <item android:id="@+id/compoundBackgroundItem"
+          android:drawable="@drawable/btn_compound_background" />
 
     <!-- Use an explicit <bitmap> to avoid scaling the icon up to the full size of the button. -->
     <item>
diff --git a/InCallUI/res/drawable/btn_compound_video_switch.xml b/InCallUI/res/drawable/btn_compound_video_switch.xml
index ef171ab..f811186 100644
--- a/InCallUI/res/drawable/btn_compound_video_switch.xml
+++ b/InCallUI/res/drawable/btn_compound_video_switch.xml
@@ -19,7 +19,8 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
     <!-- The standard "compound button" background. -->
-    <item android:drawable="@drawable/btn_compound_background" />
+    <item android:id="@+id/compoundBackgroundItem"
+          android:drawable="@drawable/btn_compound_background" />
 
     <!-- Use an explicit <bitmap> to avoid scaling the icon up to the full size of the button. -->
     <item>
diff --git a/InCallUI/res/drawable/btn_merge.xml b/InCallUI/res/drawable/btn_merge.xml
index 78e1974..2b4818a 100644
--- a/InCallUI/res/drawable/btn_merge.xml
+++ b/InCallUI/res/drawable/btn_merge.xml
@@ -18,7 +18,8 @@
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item android:drawable="@drawable/btn_background" />
+    <item android:id="@+id/backgroundItem"
+          android:drawable="@drawable/btn_background" />
 
     <item>
         <bitmap android:src="@drawable/ic_toolbar_merge"
diff --git a/InCallUI/res/drawable/btn_overflow.xml b/InCallUI/res/drawable/btn_overflow.xml
index e851ece..2eb26cc 100644
--- a/InCallUI/res/drawable/btn_overflow.xml
+++ b/InCallUI/res/drawable/btn_overflow.xml
@@ -18,7 +18,8 @@
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item android:drawable="@drawable/btn_background" />
+    <item android:id="@+id/backgroundItem"
+          android:drawable="@drawable/btn_background" />
 
     <item>
         <bitmap android:src="@drawable/ic_overflow_menu"
diff --git a/InCallUI/res/drawable/btn_swap.xml b/InCallUI/res/drawable/btn_swap.xml
index 7a82411..5d6c8ec 100644
--- a/InCallUI/res/drawable/btn_swap.xml
+++ b/InCallUI/res/drawable/btn_swap.xml
@@ -18,7 +18,8 @@
 
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
 
-    <item android:drawable="@drawable/btn_background" />
+    <item android:id="@+id/backgroundItem"
+          android:drawable="@drawable/btn_background" />
 
     <item>
         <bitmap android:src="@drawable/ic_toolbar_swap"
diff --git a/InCallUI/res/layout/call_button_fragment.xml b/InCallUI/res/layout/call_button_fragment.xml
index aa87d0c..56d65b0 100644
--- a/InCallUI/res/layout/call_button_fragment.xml
+++ b/InCallUI/res/layout/call_button_fragment.xml
@@ -35,6 +35,7 @@
     android:layout_width="match_parent"
     android:layout_margin="0dp"
     android:padding="0dp"
+    android:background="@color/button_background_color"
     android:layout_height="wrap_content"
     android:layout_alignParentBottom="true"
     android:animateLayoutChanges="true"
@@ -46,7 +47,6 @@
         android:layout_height="wrap_content"
         android:paddingStart="@dimen/button_cluster_horizontal_padding"
         android:paddingEnd="@dimen/button_cluster_horizontal_padding"
-        android:background="@color/button_background_color"
         android:gravity="bottom|center_horizontal">
 
         <!-- This row only ever shows either 4 or 5 buttons. This may depend on whether the device
diff --git a/InCallUI/res/values/colors.xml b/InCallUI/res/values/colors.xml
index f691fe2..05c2cf1 100644
--- a/InCallUI/res/values/colors.xml
+++ b/InCallUI/res/values/colors.xml
@@ -76,4 +76,31 @@
 
     <!-- 20% opacity, theme color. -->
     <color name="incall_dialpad_touch_tint">#330288d1</color>
+
+    <!-- Background colors for InCallUI. This set of colors is a subset of
+        https://spec.googleplex.com/quantumpalette#extended which pass WCAG AA and all have a
+        contrast ratio over 5:1.
+
+        These colors are also used by InCallUIMaterialColorMapUtils to generate primary
+        activity colors.
+    -->
+    <array name="background_colors">
+        <item>#00796B</item>
+        <item>#3367D6</item>
+        <item>#303F9F</item>
+        <item>#7B1FA2</item>
+        <item>#C2185B</item>
+        <item>#C53929</item>
+    </array>
+
+    <!-- Darker versions of background_colors, two shades darker. These colors are used for the
+         status bar. -->
+    <array name="background_colors_dark">
+        <item>#004D40</item>
+        <item>#1C3AA9</item>
+        <item>#1A237E</item>
+        <item>#4A148C</item>
+        <item>#880E4F</item>
+        <item>#A52714</item>
+    </array>
 </resources>