Updated error translation logic.

base/ios/nserror_util.mm

Index: base/ios/nserror_util.mm
diff --git a/base/ios/nserror_util.mm b/base/ios/nserror_util.mm
new file mode 100644
index 0000000000000000000000000000000000000000..65ea358a540d036a04ee6496cd1799e1ed574e9c
--- /dev/null
+++ b/base/ios/nserror_util.mm
@@ -0,0 +1,50 @@
+// Copyright 2015 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.
+
+#import "base/ios/nserror_util.h"
+
+#import <Foundation/Foundation.h>

[stuartmorgan, 2015/06/24 19:13:09]

Blank line after this.

[kkhorimoto, 2015/06/24 20:01:42]

Done.

+#include "base/logging.h"
+#include "base/mac/scoped_nsobject.h"
+
+namespace base {
+namespace nserror_util {
+
+namespace {
+// Iterates through |error|'s underlying errors and returns them in an array.
+NSArray* GetUnderlyingErrorChainForError(NSError* error) {
+  NSMutableArray* error_chain = [NSMutableArray array];
+  NSError* current_error = error;
+  while (current_error) {
+    [error_chain addObject:current_error];
+    current_error = current_error.userInfo[NSUnderlyingErrorKey];
+  }
+  return error_chain;
+}
+}  // namespace
+
+NSError* GetFinalUnderlyingErrorFromError(NSError* error) {
+  DCHECK(error);
+  return [GetUnderlyingErrorChainForError(error) lastObject];
+}
+
+NSError* ErrorWithAppendedUnderlyingError(NSError* original_error,
+                                          NSError* underlying_error) {
+  DCHECK(original_error && underlying_error);

[stuartmorgan, 2015/06/24 19:13:09]

Separate the DCHECKs, so that if one fails it's immediately obvious which.

[kkhorimoto, 2015/06/24 20:01:42]

Done.

+  NSArray* error_chain = GetUnderlyingErrorChainForError(original_error);
+  NSError* current_error = underlying_error;
+  for (NSInteger idx = error_chain.count - 1; idx >= 0; --idx) {
+    NSError* error = error_chain[idx];
+    scoped_nsobject<NSMutableDictionary> user_info(
+        [error.userInfo mutableCopy]);
+    [user_info setObject:current_error forKey:NSUnderlyingErrorKey];
+    current_error = [NSError errorWithDomain:error.domain
+                                        code:error.code
+                                    userInfo:user_info];
+  }
+  return current_error;
+}
+
+}  // namespace nserror_util
+}  // namespace base