Remove chrome_version.gni

File's logic has been refactored and moved to build/util/version.gni.
Logic was initially removed in issue 1501459 but file was kept to avoid
breaking downstream gn imports that were corrected in 1046349.

Depends on http://crrev/i/1046349, http://crrev/c/1524096, http://crrev/c/1501459

Bug: 919636
Test: Run gn gen with target_os="android" successfully
Change-Id: Iec00919acf6c27222bc896e6f850996cc1890a15
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1524908
Commit-Queue: Drew Stonebraker <stonebraker@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646820}

build/config/android/chrome_version.gni

-# Copyright 2018 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.
-
-import("//build/util/version.gni")