Queue callbacks in PluginService::GetPlugins.

content/browser/plugin_loader.h

Index: content/browser/plugin_loader.h
diff --git a/content/browser/plugin_loader.h b/content/browser/plugin_loader.h
new file mode 100644
index 0000000000000000000000000000000000000000..23caa10c03192677d4380ef73e1f885bc6ff6e71
--- /dev/null
+++ b/content/browser/plugin_loader.h
@@ -0,0 +1,58 @@
+// 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 CONTENT_BROWSER_PLUGIN_LOADER_H_
+#define CONTENT_BROWSER_PLUGIN_LOADER_H_
+
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "content/browser/plugin_service.h"
+#include "content/browser/utility_process_host.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace webkit {
+struct WebPluginInfo;
+}
+
+// Utility child process client that manages the IPC for loading plugins out of
+// process.
+class PluginLoader : public UtilityProcessHost::Client {
+ public:
+  PluginLoader();
+  virtual ~PluginLoader() OVERRIDE;
+
+  // Meant to be called on the IO thread. Will invoke the callback on the target
+  // loop when the plugins have been loaded.
+  void LoadPlugins(base::MessageLoopProxy* target_loop,
+                   const PluginService::GetPluginsCallback& callback);
+
+  // UtilityProcessHost::Client implementation:
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+  virtual void OnProcessCrashed(int exit_code) OVERRIDE;
+
+ private:
+  struct PendingCallback {
+    PendingCallback(scoped_refptr<base::MessageLoopProxy> loop,
+                    const PluginService::GetPluginsCallback& callback);
+    ~PendingCallback();
+
+    scoped_refptr<base::MessageLoopProxy> target_loop;
+    PluginService::GetPluginsCallback callback;
+  };
+
+  void StartLoadingIfNecessary();
+
+  void OnGotPlugins(const std::vector<webkit::WebPluginInfo>& plugins);
+
+  UtilityProcessHost* process_host_;
+  std::vector<PendingCallback> callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(PluginLoader);
+};
+
+#endif  // CONTENT_BROWSER_PLUGIN_LOADER_H_