Fix overdraw in Dialer

* Set window background to null per framework advice to reduce
overdraw
* Remove unnecessary background layers
* Fix the slightly deeper gray background above the searchbox
Bug: 10446771

Change-Id: Ie11db155593c7ea2118141aec876da37be35a7d5
diff --git a/src/com/android/dialer/DialtactsActivity.java b/src/com/android/dialer/DialtactsActivity.java
index f302f29..363adda 100644
--- a/src/com/android/dialer/DialtactsActivity.java
+++ b/src/com/android/dialer/DialtactsActivity.java
@@ -298,6 +298,7 @@
         fixIntent(intent);
 
         setContentView(R.layout.dialtacts_activity);
+        getWindow().setBackgroundDrawable(null);
 
         getActionBar().hide();