Build libmonochrome.so with secondary toolchain

chrome/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("//chrome/android/chrome_public_apk_tmpl.gni")
 import("//chrome/common/features.gni")
 import("//chrome/version.gni")
@@ skipping 436 matching lines @@
   ]
 
   if (is_android && use_order_profiling) {
     deps += [ "//tools/cygprofile" ]
   }
 
   public_configs = extra_chrome_shared_library_configs
 }
 
 # GYP: none
-if (!defined(webview_only_libmonochrome) || !webview_only_libmonochrome) {
+#
+# Only 32-bit //chrome/android/monochrome is needed, beside
+# being built with 32-bit default toolchain, it is also built
+# with secondary 32-bit toolchain in 64-bit platform because we
+# need 64-bit //android_webview/monochrome and 32-bit this target
+# for 64-bit APK.
+if (!android_64bit_target_cpu ||
+    current_toolchain == android_secondary_abi_toolchain) {
   shared_library("monochrome") {
     sources = chrome_apk_gypi.monochrome_app_native_sources
     deps = [
       "//android_webview:common",
       "//chrome:chrome_android_core",
     ]
 
     configs -= [ "//build/config/android:hide_native_jni_exports" ]
     if (is_android && use_order_profiling) {
       deps += [ "//tools/cygprofile" ]
     }
 
     public_configs = extra_chrome_shared_library_configs
   }
+} else {
+  group("monochrome_secondary_abi_lib") {
+    public_deps = [
+      ":monochrome($android_secondary_abi_toolchain)",
+    ]
+  }
 }
 
 # GYP: //chrome/android/chrome_apk.gyp:libchrome_sync_shell
 shared_library("chrome_sync_shell") {
   testonly = true
   deps = [
     "//build/config/sanitizers:deps",
     "//chrome:chrome_android_core",
     "//sync",
     "//sync:test_support_sync_fake_server_android",
@@ skipping 120 matching lines @@
     apk_name = "ChromeSyncShellTest"
     apk_under_test = ":chrome_sync_shell_apk"
     android_manifest = chrome_sync_shell_test_apk_manifest
     android_manifest_dep = ":chrome_sync_shell_test_apk_manifest"
     deps = [
       ":chrome_sync_shell_test_apk_java",
     ]
     proguard_enabled = !is_java_debug
   }
 }