Make the snapshot a public dependency of v8.

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/arm.gni")
 import("//build/config/mips.gni")
 
 # Because standalone V8 builds are not supported, assume this is part of a
 # Chromium build.
@@ skipping 456 matching lines @@
   # depend on this.
   visibility = [
     ":*",
     "//:gn_visibility",
   ]
 
   deps = [
     ":js2c",
     ":js2c_experimental",
     ":js2c_extras",
+    ":v8_base",
+  ]
+  public_deps = [
+    # This should be public so downstream targets can declare the snapshot
+    # output file as their inputs.
     ":run_mksnapshot",
-    ":v8_base",
   ]
 
   sources = [
     "$target_gen_dir/libraries.cc",
     "$target_gen_dir/experimental-libraries.cc",
     "$target_gen_dir/extras-libraries.cc",
     "$target_gen_dir/snapshot.cc",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
     ":features",
     ":toolchain",
   ]
 }
 
 if (v8_use_external_startup_data) {
   source_set("v8_external_snapshot") {
     visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
     deps = [
       ":js2c",
       ":js2c_experimental",
       ":js2c_extras",
+      ":v8_base",
+    ]
+    public_deps = [
+      ":natives_blob",
       ":run_mksnapshot",
-      ":v8_base",
-      ":natives_blob",
     ]
 
     sources = [
       "src/snapshot/natives-external.cc",
       "src/snapshot/snapshot-external.cc",
     ]
 
     configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [ "//build/config/compiler:no_chromium_code" ]
     configs += [
@@ skipping 1049 matching lines @@
     ]
 
     if (v8_use_snapshot && v8_use_external_startup_data) {
       deps = [
         ":v8_base",
         ":v8_external_snapshot",
       ]
     } else if (v8_use_snapshot) {
       deps = [
         ":v8_base",
+      ]
+      # v8_snapshot should be public so downstream targets can declare the
+      # snapshot file as their input.
+      public_deps = [
         ":v8_snapshot",
       ]
     } else {
       assert(!v8_use_external_startup_data)
       deps = [
         ":v8_base",
         ":v8_nosnapshot",
       ]
     }
 
@@ skipping 15 matching lines @@
 } else {
   group("v8") {
     if (v8_use_snapshot && v8_use_external_startup_data) {
       deps = [
         ":v8_base",
         ":v8_external_snapshot",
       ]
     } else if (v8_use_snapshot) {
       deps = [
         ":v8_base",
+      ]
+      public_deps = [
         ":v8_snapshot",
       ]
     } else {
       assert(!v8_use_external_startup_data)
       deps = [
         ":v8_base",
         ":v8_nosnapshot",
       ]
     }
 
@@ skipping 41 matching lines @@
       sources += [
         "src/d8-debug.cc",
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }