Lazily initialize the v8::Isolate used by ProxyResolverV8 (in the browser process).

net/proxy/proxy_resolver_v8.h

 // Copyright (c) 2011 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.
 
 #ifndef NET_PROXY_PROXY_RESOLVER_V8_H_
 #define NET_PROXY_PROXY_RESOLVER_V8_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
 #include "net/proxy/proxy_resolver.h"
 
-namespace gin {
-class IsolateHolder;
-}  // namespace gin
-
-namespace v8 {
-class HeapStatistics;
-class Isolate;
-}  // namespace v8
-
 namespace net {
 
 // Implementation of ProxyResolver that uses V8 to evaluate PAC scripts.
-//
-// ----------------------------------------------------------------------------
-// !!! Important note on threading model:
-// ----------------------------------------------------------------------------
-// There can be only one instance of V8 running at a time. To enforce this
-// constraint, ProxyResolverV8 holds a v8::Locker during execution. Therefore
-// it is OK to run multiple instances of ProxyResolverV8 on different threads,
-// since only one will be running inside V8 at a time.
-//
-// It is important that *ALL* instances of V8 in the process be using
-// v8::Locker. If not there can be race conditions between the non-locked V8
-// instances and the locked V8 instances used by ProxyResolverV8 (assuming they
-// run on different threads).
-//
-// This is the case with the V8 instance used by chromium's renderer -- it runs
-// on a different thread from ProxyResolver (renderer thread vs PAC thread),
-// and does not use locking since it expects to be alone.
 class NET_EXPORT_PRIVATE ProxyResolverV8 : public ProxyResolver {
  public:
   // Interface for the javascript bindings.
   class NET_EXPORT_PRIVATE JSBindings {
    public:
     enum ResolveDnsOperation {
       DNS_RESOLVE,
       DNS_RESOLVE_EX,
       MY_IP_ADDRESS,
       MY_IP_ADDRESS_EX,
@@ skipping 34 matching lines @@
                      ProxyInfo* results,
                      const net::CompletionCallback& /*callback*/,
                      RequestHandle* /*request*/,
                      const BoundNetLog& net_log) override;
   void CancelRequest(RequestHandle request) override;
   LoadState GetLoadState(RequestHandle request) const override;
   void CancelSetPacScript() override;
   int SetPacScript(const scoped_refptr<ProxyResolverScriptData>& script_data,
                    const net::CompletionCallback& /*callback*/) override;
 
-  // Create an isolate to use for the proxy resolver. If the embedder invokes
-  // this method multiple times, it must be invoked in a thread safe manner,
-  // e.g. always from the same thread.
-  static void EnsureIsolateCreated();
-
-  static v8::Isolate* GetDefaultIsolate();
-
   // Get total/ued heap memory usage of all v8 instances used by the proxy
   // resolver.
   static size_t GetTotalHeapSize();
   static size_t GetUsedHeapSize();
 
  private:
-  static gin::IsolateHolder* g_proxy_resolver_isolate_;
-
   // Context holds the Javascript state for the most recently loaded PAC
   // script. It corresponds with the data from the last call to
   // SetPacScript().
   class Context;
 
   scoped_ptr<Context> context_;
 
   JSBindings* js_bindings_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyResolverV8);
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_RESOLVER_V8_H_