Replace web_cache_messages.h with Mojo service.

components/web_cache/renderer/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.
 
 source_set("renderer") {
   sources = [
     "web_cache_render_process_observer.cc",
     "web_cache_render_process_observer.h",
   ]
 
   deps = [
     "//base",
-    "//components/web_cache/common",
+    "//components/web_cache/public/interfaces",
     "//content/public/renderer",
     "//third_party/WebKit/public:blink",
   ]
 }