Use a background for the main search box in the experimental app list.

ui/app_list/app_list_constants.cc

Index: ui/app_list/app_list_constants.cc
diff --git a/ui/app_list/app_list_constants.cc b/ui/app_list/app_list_constants.cc
index d762801f69359af5ac49c1619c35f0db7abd0b14..08559ad636c05e93da17d7678537b4797f274330 100644
--- a/ui/app_list/app_list_constants.cc
+++ b/ui/app_list/app_list_constants.cc
@@ -32,9 +32,6 @@ const SkColor kResultURLTextColor = SkColorSetRGB(0x00, 0x99, 0x33);
 const SkColor kGridTitleColor = SkColorSetRGB(0x5A, 0x5A, 0x5A);
 const SkColor kGridTitleHoverColor = SkColorSetRGB(0x3C, 0x3C, 0x3C);
 
-// Color of the borders used in the experimental app list start page.
-const SkColor kStartPageBorderColor = SkColorSetRGB(0xEE, 0xEE, 0xEE);
-
 // Color of the folder ink bubble.
 const SkColor kFolderBubbleColor = SkColorSetRGB(0xD7, 0xD7, 0xD7);