Move Ash-specific vector icon files into a separate directory

ui/gfx/vector_icons/shelf_overview.1x.icon

Index: ui/gfx/vector_icons/shelf_overview.1x.icon
diff --git a/ui/gfx/vector_icons/shelf_overview.1x.icon b/ui/gfx/vector_icons/shelf_overview.1x.icon
deleted file mode 100644
index f443ef1b1fa62faad5f1677c1795f3693dc7029d..0000000000000000000000000000000000000000
--- a/ui/gfx/vector_icons/shelf_overview.1x.icon
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-CANVAS_DIMENSIONS, 16,
-MOVE_TO, 2, 3,
-R_CUBIC_TO, -0.53f, 0, -1, 0.45f, -1, 1,
-R_V_LINE_TO, 8,
-R_CUBIC_TO, 0, 0.55f, 0.47f, 1, 1, 1,
-R_H_LINE_TO, 8,
-R_CUBIC_TO, 0.53f, 0, 1, -0.45f, 1, -1,
-V_LINE_TO, 4,
-R_CUBIC_TO, 0, -0.55f, -0.47f, -1, -1, -1,
-H_LINE_TO, 2,
-CLOSE,
-R_MOVE_TO, 1, 8,
-V_LINE_TO, 5,
-R_H_LINE_TO, 6,
-R_V_LINE_TO, 6,
-H_LINE_TO, 3,
-CLOSE,
-MOVE_TO, 12.29f, 13,
-R_CUBIC_TO, 0.39f, 0, 0.71f, -0.45f, 0.71f, -1.01f,
-V_LINE_TO, 4.01f,
-CUBIC_TO, 13, 3.45f, 12.68f, 3, 12.29f, 3,
-H_LINE_TO, 12,
-R_V_LINE_TO, 10,
-R_H_LINE_TO, 0.29f,
-CLOSE,
-MOVE_TO, 14.29f, 13,
-R_CUBIC_TO, 0.39f, 0, 0.71f, -0.45f, 0.71f, -1.01f,
-V_LINE_TO, 4.01f,
-CUBIC_TO, 15, 3.45f, 14.68f, 3, 14.29f, 3,
-H_LINE_TO, 14,
-R_V_LINE_TO, 10,
-R_H_LINE_TO, 0.29f,
-CLOSE,
-END