Add GN template for android_assets(). Use it in content_shell_apk.

content/shell/android/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("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
 import("//build_overrides/v8.gni")
 import("//third_party/icu/config.gni")
 
 generate_jni("content_shell_jni_headers") {
@@ skipping 92 matching lines @@
   }
   if (v8_use_external_startup_data) {
     sources += [
       "$root_out_dir/natives_blob.bin",
       "$root_out_dir/snapshot_blob.bin",
     ]
     deps += [ "//v8" ]
   }
 }
 
+android_assets("content_shell_assets") {
+  deps = [
+    "//base:icu_assets",
+    "//content/shell:pak",
+    "//gin:v8_snapshot_assets",
+  ]
+  sources = [
+    "$root_build_dir/content_shell.pak",
+  ]
+  enable_compression = false
+}
+
 android_apk("content_shell_apk") {
   testonly = true
   data_deps = [
     # "//tools/android/forwarder",
   ]
   deps = [
     ":content_shell_apk_java",
     ":content_shell_apk_resources",
+    ":content_shell_assets",
     ":content_shell_java",
     ":content_shell_manifest",
-    ":copy_content_shell_assets",
     ":libcontent_shell_content_view",
     "//base:base_java",
     "//content/public/android:content_java",
     "//media/base/android:media_java",
     "//net/android:net_java",
 
     #"//third_party/mesa:osmesa_in_lib_dir",
     "//ui/android:ui_java",
   ]
   apk_name = "ContentShell"
   android_manifest = content_shell_manifest
   native_libs = [ "libcontent_shell_content_view.so" ]
-  asset_location = content_shell_assets_dir
 
   # TODO(GYP)
   #'extra_native_libs': ['<(SHARED_LIB_DIR)/libosmesa.so'],
 }
 
 android_library("content_shell_test_java") {
   testonly = true
   deps = [
     ":content_shell_java",
     ":content_shell_apk_java",
@@ skipping 84 matching lines @@
 
   # GYP: //content/content_tests.gypi:chromium_android_linker_test_jni_headers
   generate_jni("linker_test_jni_headers") {
     testonly = true
     jni_package = "content/shell"
     sources = [
       "linker_test_apk/src/org/chromium/chromium_linker_test_apk/LinkerTests.java",
     ]
   }
 }