Download and copy shell binary on Android as well as Linux.

mojo/public/tools/BUILD.gn

 # 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("../mojo.gni")
 
 if (use_prebuilt_mojo_shell) {
   copy("copy_mojo_shell") {
     filename = "mojo_shell"
     if (is_win) {
       filename += ".exe"
     }
+    if (is_android) {
+      filename = "MojoShell.apk"
+    }
     sources = [
       "prebuilt/$filename",
     ]
-    outputs = [
-      "$root_out_dir/$filename",
-    ]
+    if (is_android) {
+      outputs = [
+        "$root_out_dir/apks/$filename",
+      ]
+    } else {
+      outputs = [
+        "$root_out_dir/$filename",
+      ]
+    }
   }
 }