Fix DexLoaderTest#testLoadAfterDeleteCachedDexes() flakiness

chrome/android/webapk/shell_apk/javatests/canary_lib/BUILD.gn

 # Copyright 2016 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/rules.gni")
 
 android_library("canary_lib") {
   dex_path = "$target_gen_dir/canary.dex"
   java_files = [ "src/org/chromium/webapk/shell_apk/test/canary/Canary.java" ]
 }
 
-# dex asset added to dex_optimizer_apk in order to test creating ClassLoader
+android_library("canary_lib2") {
+  dex_path = "$target_gen_dir/canary2.dex"
+  java_files = [ "src/org/chromium/webapk/shell_apk/test/canary/Canary2.java" ]
+}
+
+# dex assets added to dex_optimizer_apk in order to test creating ClassLoader
 # from .dex in remote APK.
+
 android_assets("canary_dex_asset") {
   sources = [
     "$target_gen_dir/canary.dex",
   ]
   disable_compression = true
   deps = [
     ":canary_lib",
   ]
 }
+
+android_assets("canary_dex_asset2") {
+  sources = [
+    "$target_gen_dir/canary2.dex",
+  ]
+  disable_compression = true
+  deps = [
+    ":canary_lib2",
+  ]
+}