Revert of android: Introduce a ui::PlatformWindow implementation for android.

ui/platform_window/BUILD.gn

Index: ui/platform_window/BUILD.gn
diff --git a/ui/platform_window/BUILD.gn b/ui/platform_window/BUILD.gn
index 438a38256e938417bfa5ec16a6f9086b508b6e20..2d9680b3d3e9b829d58ba571a17f5eefb7bfa53b 100644
--- a/ui/platform_window/BUILD.gn
+++ b/ui/platform_window/BUILD.gn
@@ -1,8 +1,6 @@
 # Copyright 2014 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/config/ui.gni")
 
 source_set("platform_window") {
   sources = [
@@ -16,20 +14,3 @@
     "//ui/gfx",
   ]
 }
-
-component("platform_impls") {
-  if (is_android) {
-    deps = [
-      "//ui/platform_window/android",
-      "//ui/platform_window/android:jni_headers",
-    ]
-  } else if (use_x11) {
-    deps = [
-      "//ui/platform_window/x11",
-    ]
-  } else if (is_win) {
-    deps = [
-      "//ui/platform_window/win",
-    ]
-  }
-}