Extracted inner class doing process dispatch.

chrome/browser/web_resource/json_asynchronous_unpacker.cc

+// Copyright (c) 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 "chrome/browser/web_resource/json_asynchronous_unpacker.h"
+
+#include "base/command_line.h"
+#include "chrome/browser/web_resource/web_resource_service.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/chrome_utility_messages.h"
+#include "chrome/common/web_resource/web_resource_unpacker.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/resource_dispatcher_host.h"
+#include "content/public/browser/utility_process_host.h"
+#include "content/public/browser/utility_process_host_client.h"
+
+using content::BrowserThread;
+using content::UtilityProcessHost;
+using content::UtilityProcessHostClient;
+
+// This class coordinates a web resource unpack and parse task which is run in
+// a separate process.  Results are sent back to this class and routed to
+// the WebResourceService.
+class JSONAsynchronousUnpackerImpl
+    : public UtilityProcessHostClient,
+      public JSONAsynchronousUnpacker {
+ public:
+  explicit JSONAsynchronousUnpackerImpl(
+      JSONAsynchronousUnpackerDelegate* delegate)
+    : JSONAsynchronousUnpacker(delegate),
+      got_response_(false) {
+  }
+
+  void Start(const std::string& json_data) {
+    AddRef();  // balanced in Cleanup.
+
+    // TODO(willchan): Look for a better signal of whether we're in a unit test
+    // or not. Using |ResourceDispatcherHost::Get()| for this is pretty lame.
+    // If we don't have a ResourceDispatcherHost, assume we're in a test and
+    // run the unpacker directly in-process.
+    bool use_utility_process =
+        content::ResourceDispatcherHost::Get() &&
+        !CommandLine::ForCurrentProcess()->HasSwitch(switches::kSingleProcess);
+    if (use_utility_process) {
+      BrowserThread::ID thread_id;
+      CHECK(BrowserThread::GetCurrentThreadIdentifier(&thread_id));
+      BrowserThread::PostTask(
+          BrowserThread::IO, FROM_HERE,
+          base::Bind(
+              &JSONAsynchronousUnpackerImpl::StartProcessOnIOThread,
+              this, thread_id, json_data));
+    } else {
+      WebResourceUnpacker unpacker(json_data);
+      if (unpacker.Run()) {
+        OnUnpackWebResourceSucceeded(*unpacker.parsed_json());
+      } else {
+        OnUnpackWebResourceFailed(unpacker.error_message());
+      }
+    }
+  }
+
+ private:
+  virtual ~JSONAsynchronousUnpackerImpl() {}
+
+  // UtilityProcessHostClient.
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE {
+    bool handled = true;
+    IPC_BEGIN_MESSAGE_MAP(JSONAsynchronousUnpackerImpl, message)
+      IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_UnpackWebResource_Succeeded,
+                          OnUnpackWebResourceSucceeded)
+      IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_UnpackWebResource_Failed,
+                          OnUnpackWebResourceFailed)
+      IPC_MESSAGE_UNHANDLED(handled = false)
+    IPC_END_MESSAGE_MAP()
+    return handled;
+  }
+
+  virtual void OnProcessCrashed(int exit_code) OVERRIDE {
+    if (got_response_)
+      return;
+
+    OnUnpackWebResourceFailed(
+        "Utility process crashed while trying to retrieve web resources.");
+  }
+
+  void OnUnpackWebResourceSucceeded(
+      const DictionaryValue& parsed_json) {
+    if (delegate_)
+      delegate_->OnUnpackFinished(parsed_json);
+    Cleanup();
+  }
+
+  void OnUnpackWebResourceFailed(const std::string& error_message) {
+    if (delegate_)
+      delegate_->OnUnpackError(error_message);
+    Cleanup();
+  }
+
+  // Release reference and set got_response_.
+  void Cleanup() {
+    DCHECK(!got_response_);
+    got_response_ = true;
+    Release();
+  }
+
+  void StartProcessOnIOThread(BrowserThread::ID thread_id,
+                              const std::string& json_data) {
+    UtilityProcessHost* host = UtilityProcessHost::Create(this, thread_id);
+    host->EnableZygote();
+    // TODO(mrc): get proper file path when we start using web resources
+    // that need to be unpacked.
+    host->Send(new ChromeUtilityMsg_UnpackWebResource(json_data));
+  }
+
+  // True if we got a response from the utility process and have cleaned up
+  // already.
+  bool got_response_;
+};
+
+JSONAsynchronousUnpacker* JSONAsynchronousUnpacker::Create(
+    JSONAsynchronousUnpackerDelegate* delegate) {
+  return new JSONAsynchronousUnpackerImpl(delegate);
+}
+