Simplifying some launcher themes

> Replacing some colors with theme attributes
> Simplifying styles definition by removing unnecessary inheritance and inlining some definitions

Change-Id: Ifa167515cae6a7fd3720f1a52ff9ce11abb4495f

src/com/android/launcher3/graphics/DrawableFactory.java

@@ -77,7 +77,7 @@ public class DrawableFactory {
         if (mPreloadProgressPath == null) {
             mPreloadProgressPath = getPreloadProgressPath(context);
         }
-        return new PreloadIconDrawable(icon, mPreloadProgressPath);
+        return new PreloadIconDrawable(icon, mPreloadProgressPath, context);
     }