Enable external V8 snapshot on Android through GN.

content/shell/android/BUILD.gn

Index: content/shell/android/BUILD.gn
diff --git a/content/shell/android/BUILD.gn b/content/shell/android/BUILD.gn
index 6a81b30eaf7b960f5dd76d296a3f06c6f2a9ce8a..882955ecde977a1840cd3e72c0b7da3a2042669e 100644
--- a/content/shell/android/BUILD.gn
+++ b/content/shell/android/BUILD.gn
@@ -4,6 +4,7 @@
 
 import("//build/config/android/config.gni")
 import("//build/config/android/rules.gni")
+import("//build/module_args/v8.gni")
 import("//third_party/icu/config.gni")
 
 generate_jni("content_shell_jni_headers") {
@@ -94,6 +95,12 @@ copy_ex("copy_content_shell_assets") {
       "$root_build_dir/icudtl.dat"
     ]
   }
+  if (v8_use_external_startup_data) {
+    sources += [
+      "$root_gen_dir/natives_blob.bin",
+      "$root_gen_dir/snapshot_blob.bin",
+    ]
+  }
 }
 
 android_apk("content_shell_apk") {