Redesign cloud printing subsystem layer.

chrome/service/cloud_print/print_system.h

Index: chrome/service/cloud_print/print_system.h
===================================================================
--- chrome/service/cloud_print/print_system.h	(revision 48641)
+++ chrome/service/cloud_print/print_system.h	(working copy)
@@ -2,14 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_SERVICE_CLOUD_PRINT_PRINTER_INFO_H_
-#define CHROME_SERVICE_CLOUD_PRINT_PRINTER_INFO_H_
+#ifndef CHROME_SERVICE_CLOUD_PRINT_PRINT_SYSTEM_H_
+#define CHROME_SERVICE_CLOUD_PRINT_PRINT_SYSTEM_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/file_path.h"
+#include "base/ref_counted.h"
 
 // This is the interface for platform-specific code for cloud print
 namespace cloud_print {
@@ -70,58 +71,98 @@
   }
 };
 
-// Enumerates the list of installed local and network printers.
-void EnumeratePrinters(PrinterList* printer_list);
-// Gets the capabilities and defaults for a specific printer.
-bool GetPrinterCapsAndDefaults(const std::string& printer_name,
-                               PrinterCapsAndDefaults* printer_info);
-bool ValidatePrintTicket(const std::string& printer_name,
-                         const std::string& print_ticket_data);
-std::string GenerateProxyId();
-bool SpoolPrintJob(const std::string& print_ticket,
-                   const FilePath& print_data_file_path,
-                   const std::string& print_data_mime_type,
-                   const std::string& printer_name,
-                   const std::string& job_title,
-                   PlatformJobId* job_id_ret);
+// PrintSystem class will provide interface for different printing systems
+// (Windows, CUPS) to implement. User will call CreateInstance() to
+// obtain available printing system.
+// Please note, that PrintSystem is not platform specific, but rather
+// print system specific. For example, CUPS is available on both Linux and Mac,
+// but not avaialble on ChromeOS, etc. This design allows us to add more
+// functionality on some platforms, while reusing core (CUPS) functions.
+class PrintSystem : public base::RefCountedThreadSafe<PrintSystem> {
+ public:
+  virtual ~PrintSystem() {}
 
-bool GetJobDetails(const std::string& printer_name,
-                   PlatformJobId job_id,
-                   PrintJobDetails *job_details);
-bool IsValidPrinter(const std::string& printer_name);
+  // Enumerates the list of installed local and network printers.
+  virtual void EnumeratePrinters(PrinterList* printer_list) = 0;
 
-// A class that watches changes to a printer or a print server.
-// The set of notifications are very coarse-grained (even though the Windows
-// API allows for listening to fine-grained details about a printer, this class
-// does not support that level of fine-grained control.
-class PrinterChangeNotifier {
- public:
-  class Delegate {
-    public:
-      virtual void OnPrinterAdded() = 0;
-      virtual void OnPrinterDeleted() = 0;
-      virtual void OnPrinterChanged() = 0;
-      virtual void OnJobChanged() = 0;
+  // Gets the capabilities and defaults for a specific printer.
+  virtual bool GetPrinterCapsAndDefaults(const std::string& printer_name,
+                                     PrinterCapsAndDefaults* printer_info) = 0;
+
+  // Returns true if ticket is valid.
+  virtual bool ValidatePrintTicket(const std::string& printer_name,
+                                   const std::string& print_ticket_data) = 0;
+
+  // Send job to the printer.
+  virtual bool SpoolPrintJob(const std::string& print_ticket,
+                             const FilePath& print_data_file_path,
+                             const std::string& print_data_mime_type,
+                             const std::string& printer_name,
+                             const std::string& job_title,
+                             PlatformJobId* job_id_ret) = 0;
+
+  // Get details for already spooled job.
+  virtual bool GetJobDetails(const std::string& printer_name,
+                             PlatformJobId job_id,
+                             PrintJobDetails *job_details) = 0;
+
+  // Returns true if printer_name points to a valid printer.
+  virtual bool IsValidPrinter(const std::string& printer_name) = 0;
+
+  class PrintServerWatcher
+      : public base::RefCountedThreadSafe<PrintServerWatcher> {
+   public:
+    // Callback interface for new printer notifications.
+    class Delegate {
+      public:
+        virtual void OnPrinterAdded() = 0;
+        // TODO(gene): Do we need OnPrinterDeleted notification here?
+    };
+
+    virtual ~PrintServerWatcher() {}
+    virtual bool StartWatching(PrintServerWatcher::Delegate* delegate) = 0;
+    virtual bool StopWatching() = 0;
   };
-  PrinterChangeNotifier();
-  ~PrinterChangeNotifier();
-  bool StartWatching(const std::string& printer_name, Delegate* delegate);
-  bool StopWatching();
-  bool GetCurrentPrinterInfo(PrinterBasicInfo* printer_info);
- private:
-  // Internal state maintained by the PrinterChangeNotifier class.
-  class NotificationState;
-  NotificationState* state_;
-  DISALLOW_COPY_AND_ASSIGN(PrinterChangeNotifier);
+
+  class PrinterWatcher : public base::RefCountedThreadSafe<PrinterWatcher> {
+   public:
+    // Callback interface for printer updates notifications.
+    class Delegate {
+      public:
+        virtual void OnPrinterDeleted() = 0;
+        virtual void OnPrinterChanged() = 0;
+        virtual void OnJobChanged() = 0;
+    };
+
+    virtual ~PrinterWatcher() {}
+    virtual bool StartWatching(PrinterWatcher::Delegate* delegate) = 0;
+    virtual bool StopWatching() = 0;
+    virtual bool GetCurrentPrinterInfo(PrinterBasicInfo* printer_info) = 0;
+  };
+
+  // Factory methods to create corresponding watcher. Callee is responsible
+  // for deleting objects. Return NULL if failed.
+  virtual PrintServerWatcher* CreatePrintServerWatcher() = 0;
+  virtual PrinterWatcher* CreatePrinterWatcher(
+      const std::string& printer_name) = 0;
+
+  // Generate unique for proxy.
+  static std::string GenerateProxyId();
+
+  // Call this function to obtain current printing system. Return NULL if no
+  // print system available. Delete returned PrintSystem pointer using delete.
+  static scoped_refptr<PrintSystem> CreateInstance();
 };
 
+
 // This typedef is to workaround the issue with certain versions of
 // Visual Studio where it gets confused between multiple Delegate
 // classes and gives a C2500 error. (I saw this error on the try bots -
 // the workaround was not needed for my machine).
-typedef PrinterChangeNotifier::Delegate PrinterChangeNotifierDelegate;
+typedef PrintSystem::PrintServerWatcher::Delegate PrintServerWatcherDelegate;
+typedef PrintSystem::PrinterWatcher::Delegate PrinterWatcherDelegate;
 
 }  // namespace cloud_print
 
-#endif  // CHROME_SERVICE_CLOUD_PRINT_PRINTER_INFO_H_
+#endif  // CHROME_SERVICE_CLOUD_PRINT_PRINT_SYSTEM_H_