[Sync] Add support for sync Persistence Errors

sync/api/sync_error.h

 // Copyright 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.
 
 #ifndef SYNC_API_SYNC_ERROR_H_
 #define SYNC_API_SYNC_ERROR_H_
 
 #include <iosfwd>
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "sync/base/sync_export.h"
 #include "sync/internal_api/public/base/model_type.h"
 
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
 namespace syncer {
 
 // Sync errors are used for debug purposes and handled internally and/or
-// exposed through Chrome's "about:sync" internal page. They are considered
-// unrecoverable for the datatype creating them, and should only be used as
-// such.
+// exposed through Chrome's "about:sync" internal page.
 // This class is copy-friendly and thread-safe.
 class SYNC_EXPORT SyncError {
  public:
+  // Error types are used to distinguish general datatype errors (which result
+  // in the datatype being disabled) from actionable sync errors (which might
+  // have more complicated results).
+  enum ErrorType {
+    UNSET,                // No error.
+    UNRECOVERABLE_ERROR,  // An unrecoverable runtime error was encountered, and
+                          // sync should be disabled completely.
+    DATATYPE_ERROR,       // A datatype error was encountered, and the datatype
+                          // should be disabled.
+    PERSISTENCE_ERROR,    // A persistence error was detected, and the
+                          // datataype should be associated after a sync update.
+    CRYPTO_ERROR,         // A cryptographer error was detected, and the
+                          // datatype should be associated after it is resolved.
+  };
+
   // Default constructor refers to "no error", and IsSet() will return false.
   SyncError();
 
-  // Create a new Sync error triggered by datatype |type| with debug message
-  // |message| from the specified location. IsSet() will return true.
-  // Will print the new error to LOG(ERROR).
+  // Create a new Sync error of type |error_type| triggered by |model_type|
+  // from the specified location. IsSet() will return true afterward. Will
+  // create and print an error specific message to LOG(ERROR).
   SyncError(const tracked_objects::Location& location,
+            ErrorType error_type,
             const std::string& message,
-            ModelType type);
+            ModelType model_type);
 
   // Copy and assign via deep copy.
   SyncError(const SyncError& other);
   SyncError& operator=(const SyncError& other);
 
   ~SyncError();
 
-  // Reset the current error to a new error. May be called irrespective of
-  // whether IsSet() is true. After this is called, IsSet() will return true.
+  // Reset the current error to a new datatype error. May be called
+  // irrespective of whether IsSet() is true. After this is called, IsSet()
+  // will return true.
   // Will print the new error to LOG(ERROR).
   void Reset(const tracked_objects::Location& location,
              const std::string& message,
              ModelType type);
 
   // Whether this is a valid error or not.
   bool IsSet() const;
 
   // These must only be called if IsSet() is true.
   const tracked_objects::Location& location() const;
   const std::string& message() const;
-  ModelType type() const;
+  ModelType model_type() const;
+  ErrorType error_type() const;
 
   // Returns empty string is IsSet() is false.
   std::string ToString() const;
  private:
   // Print error information to log.
   void PrintLogError() const;
 
   // Make a copy of a SyncError. If other.IsSet() == false, this->IsSet() will
   // now return false.
   void Copy(const SyncError& other);
 
   // Initialize the local error data with the specified error data. After this
   // is called, IsSet() will return true.
   void Init(const tracked_objects::Location& location,
             const std::string& message,
-            ModelType type);
+            ModelType model_type,
+            ErrorType error_type);
 
   // Reset the error to it's default (unset) values.
   void Clear();
 
   // scoped_ptr is necessary because Location objects aren't assignable.
   scoped_ptr<tracked_objects::Location> location_;
   std::string message_;
-  ModelType type_;
+  ModelType model_type_;
+  ErrorType error_type_;
 };
 
 // gmock printer helper.
 SYNC_EXPORT void PrintTo(const SyncError& sync_error, std::ostream* os);
 
 }  // namespace syncer
 
 #endif  // SYNC_API_SYNC_ERROR_H_