Convert the PluginService interface to be an async wrapper around PluginList.

chrome/browser/metrics/metrics_service.h

Index: chrome/browser/metrics/metrics_service.h
diff --git a/chrome/browser/metrics/metrics_service.h b/chrome/browser/metrics/metrics_service.h
index 46867ed717d9706d379ae6e683a6708b5d9a16e6..4323daa3c6a20390042b99b9a33ba99b392c7677 100644
--- a/chrome/browser/metrics/metrics_service.h
+++ b/chrome/browser/metrics/metrics_service.h
@@ -37,6 +37,7 @@ class TemplateURLService;
 namespace base {
 class DictionaryValue;
 class ListValue;
+class MessageLoopProxy;
 }
 
 namespace webkit {
@@ -154,18 +155,36 @@ class MetricsService : public NotificationObserver,
     SENDING_CURRENT_LOGS,   // Sending standard current logs as they acrue.
   };
 
+  // When in the INIT_TASK_SCHEDULED state, multiple tasks are performed. In the

[jam, 2011/09/21 00:04:51]

are all these changes really necessary? can't we keep metrics service the same,
and just do the plugins/hwclass tasks serially to minimize the changes from this
cl?

[Robert Sesek, 2011/09/21 01:13:44]

Ok. Made the init tasks serial.

+  // completion callback, when all init tasks are done, the service moves to
+  // INIT_TASK_DONE.
+  enum InitSubtaskState {
+    INIT_SUBTASK_UNSTARTED = 0,       // Init subtasks have not been started.
+    INIT_SUBTASK_PLUGINS   = 1 << 0,  // Finished loading the plugin list.
+    INIT_SUBTASK_HWCLASS   = 1 << 1,  // Finished loading the hardware class.
+    INIT_SUBTASK_ALL       = INIT_SUBTASK_PLUGINS | INIT_SUBTASK_HWCLASS,
+  };
+
   enum ShutdownCleanliness {
     CLEANLY_SHUTDOWN = 0xdeadbeef,
     NEED_TO_SHUTDOWN = ~CLEANLY_SHUTDOWN
   };
 
-  class InitTask;
-  class InitTaskComplete;
+  // Method that is run as a delayed task after the MetricsService is
+  // constructed to perform initialization tasks.
+  void RunInitTasks();
+
+  // Called on the FILE thread to load hardware class information.
+  void InitTaskGetHardwareClass(base::MessageLoopProxy* target_loop);
 
-  // Callback to let us know that the init task is done.
-  void OnInitTaskComplete(
-      const std::string& hardware_class,
-      const std::vector<webkit::WebPluginInfo>& plugins);
+  // Callbacks to let us know that the init task is done.
+  void OnInitTaskGotHardwareClass(const std::string& hardware_class);
+  void OnInitTaskGotPluginInfo(
+      std::vector<webkit::WebPluginInfo> plugins);
+
+  // Moves the |state_| to INIT_TASK_DONE if all the init subtasks have
+  // completed.
+  void OnInitTaskMaybeDone();
 
   // When we start a new version of Chromium (different from our last run), we
   // need to discard the old crash stats so that we don't attribute crashes etc.
@@ -358,6 +377,9 @@ class MetricsService : public NotificationObserver,
   // state.
   State state_;
 
+  // The state of the init subtask.
+  uint32 init_state_;
+
   // Chrome OS hardware class (e.g., hardware qualification ID). This
   // class identifies the configured system components such as CPU,
   // WiFi adapter, etc.  For non Chrome OS hosts, this will be an