Sync: Display non-severe errors on about:sync in gray color rather than red.

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>
 
@@ skipping 20 matching lines @@
     UNRECOVERABLE_ERROR,  // An unrecoverable runtime error was encountered, and
                           // sync should be disabled and purged completely.
     DATATYPE_ERROR,       // A datatype error was encountered, and the datatype
                           // should be disabled and purged completely. Note that
                           // datatype errors may be reset, triggering a
                           // re-enable.
     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.
-    UNREADY_ERROR,        // The type is not ready to start yet, so should be
+    UNREADY_ERROR,        // A datatype is not ready to start yet, so should be
                           // neither purged nor enabled until it is ready.
+    DATATYPE_POLICY_ERROR // A datatype should be disabled and purged due
+                          // to configuration constraints.
+  };
+
+  // Severity is used to indicate how an error should be logged and
+  // represented to an end user.
+  enum Severity {
+    SYNC_ERROR_SEVERITY_ERROR,  // Severe unrecoverable error.
+    SYNC_ERROR_SEVERITY_INFO    // Low-severity recoverable error or
+                                // configuration policy issue.
   };
 
   // Default constructor refers to "no error", and IsSet() will return false.
   SyncError();
 
   // 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,
@@ skipping 16 matching lines @@
 
   // 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 model_type() const;
   ErrorType error_type() const;
 
+  // Error severity for logging and UI purposes.
+  Severity GetSeverity() const;
+  // Type specific message prefix for logging and UI purposes.
+  std::string GetMessagePrefix() 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);
 
@@ skipping 13 matching lines @@
   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_