Simplify the user agent code some more since after r255534 it's not affected by the site's URL.

webkit/common/user_agent/user_agent.cc

-// Copyright 2012 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.
-
-#include "webkit/common/user_agent/user_agent.h"
-
-#include "base/lazy_instance.h"
-#include "base/logging.h"
-#include "base/synchronization/lock.h"
-
-namespace webkit_glue {
-
-namespace {
-
-class UserAgentState {
- public:
-  UserAgentState();
-  ~UserAgentState();
-
-  void Set(const std::string& user_agent);
-  const std::string& Get() const;
-
- private:
-  mutable std::string user_agent_;
-
-  mutable bool user_agent_requested_;
-
-  // This object can be accessed from multiple threads, so use a lock around
-  // accesses to the data members.
-  mutable base::Lock lock_;
-};
-
-UserAgentState::UserAgentState()
-    : user_agent_requested_(false) {
-}
-
-UserAgentState::~UserAgentState() {
-}
-
-void UserAgentState::Set(const std::string& user_agent) {
-  base::AutoLock auto_lock(lock_);
-  if (user_agent == user_agent_) {
-    // We allow the user agent to be set multiple times as long as it
-    // is set to the same value, in order to simplify unit testing
-    // given g_user_agent is a global.
-    return;
-  }
-  DCHECK(!user_agent.empty());
-  DCHECK(!user_agent_requested_) << "Setting the user agent after someone has "
-      "already requested it can result in unexpected behavior.";
-  user_agent_ = user_agent;
-}
-
-const std::string& UserAgentState::Get() const {
-  base::AutoLock auto_lock(lock_);
-  user_agent_requested_ = true;
-
-  DCHECK(!user_agent_.empty());
-
-  return user_agent_;
-}
-
-base::LazyInstance<UserAgentState> g_user_agent = LAZY_INSTANCE_INITIALIZER;
-
-}  // namespace
-
-void SetUserAgent(const std::string& user_agent) {
-  g_user_agent.Get().Set(user_agent);
-}
-
-const std::string& GetUserAgent(const GURL& url) {
-  return g_user_agent.Get().Get();
-}
-
-}  // namespace webkit_glue