Add superficial unit test for PrintJob. That's a start....

chrome/browser/printing/print_job.h

 // Copyright (c) 2006-2008 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 CHROME_BROWSER_PRINTING_PRINT_JOB_H_
 #define CHROME_BROWSER_PRINTING_PRINT_JOB_H_
 
+#include "base/message_loop.h"
 #include "base/ref_counted.h"
 #include "chrome/browser/printing/print_job_worker_owner.h"
 #include "chrome/common/notification_service.h"
 
 class ChromeFont;
 class GURL;
 class Thread;
 
 namespace printing {
 
 // See definition below.
 class JobEventDetails;
 
 class PrintedDocument;
 class PrintedPage;
 class PrintedPagesSource;
 class PrintJobWorker;
 class PrinterQuery;
 
 // Manages the print work for a specific document. Talks to the printer through
 // PrintingContext though PrintJob::Worker. Hides access to PrintingContext in a
 // worker thread so the caller never blocks. PrintJob will send notifications on
 // any state change. While printing, the PrintJobManager instance keeps a
 // reference to the job to be sure it is kept alive. All the code in this class
 // runs in the UI thread.
 class PrintJob : public base::RefCountedThreadSafe<PrintJob>,
                  public NotificationObserver,
-                 public PrintJobWorkerOwner {
+                 public PrintJobWorkerOwner,
+                 public MessageLoop::DestructionObserver {
  public:
   // GetSettings() UI parameter.
   enum GetSettingsAskParam {
     DEFAULTS,
     ASK_USER,
   };
 
   // Create a standalone PrintJob. When initializing with this constructor,
   // Initialize() must not be called.
   PrintJob(PrintedPagesSource* source);
   // Create a empty PrintJob. When initializing with this constructor,
   // post-constructor initialization must be done with Initialize().
   PrintJob();
   virtual ~PrintJob();
 
+  // Grabs the ownership of the PrintJobWorker from another job, which is
+  // usually a PrinterQuery.
   void Initialize(PrintJobWorkerOwner* job, PrintedPagesSource* source);
 
   // NotificationObserver
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   // PrintJobWorkerOwner
   virtual void AddRef() {
     return base::RefCountedThreadSafe<PrintJob>::AddRef();
   }
   virtual void Release() {
     return base::RefCountedThreadSafe<PrintJob>::Release();
   }
   virtual void GetSettingsDone(const PrintSettings& new_settings,
                                PrintingContext::Result result);
   virtual PrintJobWorker* DetachWorker(PrintJobWorkerOwner* new_owner);
   virtual MessageLoop* message_loop() { return ui_message_loop_; }
   virtual const PrintSettings& settings() const { return settings_; }
   virtual int cookie() const;
 
+  // DestructionObserver
+  virtual void WillDestroyCurrentMessageLoop();
+
   // Initializes the printing context. This can be done synchronously or not. It
   // is fine to call this function multiple times to reinitialize the settings.
   // |parent_window| parameter will be the owner of the print setting dialog
   // box. It is unused when |ask_for_user_settings| is DEFAULTS. No-op if a
   // print job is active.
   void GetSettings(GetSettingsAskParam ask_user_for_settings,
                    HWND parent_window);
 
   // Starts the actual printing. Signals the worker that it should begin to
   // spool as soon as data is available.
@@ skipping 135 matching lines @@
   scoped_refptr<PrintedPage> page_;
   const Type type_;
 
   DISALLOW_COPY_AND_ASSIGN(JobEventDetails);
 };
 
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_JOB_H_