A quick fix for Issue 19421....

chrome/browser/autocomplete/autocomplete_edit_view_mac.mm

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/autocomplete/autocomplete_edit_view_mac.h"
 
 #include "app/gfx/font.h"
 #include "app/resource_bundle.h"
 #include "base/clipboard.h"
 #include "base/string_util.h"
@@ skipping 344 matching lines @@
   // One option would seem to be to check for a non-nil field
   // editor, and check it's selected range against its length.
   model_->StartAutocomplete(false);
 }
 
 void AutocompleteEditViewMac::ClosePopup() {
   popup_view_->GetModel()->StopAutocomplete();
 }
 
 void AutocompleteEditViewMac::SetText(const std::wstring& display_text) {
+  // Exit if an input method is composing text.

[rohitrao (ping after 24h), 2009/08/18 21:42:35]

Is this guaranteed to be called again once the text is unmarked?

[Hironori Bono, 2009/08/19 05:23:38]

Yes. This function is called when this NSTextField control receives a
controlTextDidChange notification. Also, when the text is unmarked, Cocoa sends
a controlTextDidChange notification to this NSTextField control.
Thus, this function is called when the text is unmarked.

+  // NSTextView finishes an ongoing composition when updating the value of an
+  // NSTextField instance. This prevents inputting non-ASCII characters which
+  // need input methods, such as Latin characters, CJK characters, etc.
+  // To prevent updating this NSTextField value while an input method is
+  // composing text, we check whether or not the field editor for this control
+  // has marked text, text being composed by an input method, and return if
+  // the editor has marked text.
+  NSTextView* text_view = static_cast<NSTextView*>([field_ currentEditor]);
+  if (text_view && [text_view hasMarkedText])
+    return;
+
   NSString* ss = base::SysWideToNSString(display_text);
   NSMutableAttributedString* as =
       [[[NSMutableAttributedString alloc] initWithString:ss] autorelease];
   NSFont* font = ResourceBundle::GetSharedInstance().GetFont(
       ResourceBundle::BaseFont).nativeFont();
   [as addAttribute:NSFontAttributeName value:font
              range:NSMakeRange(0, [as length])];
 
   url_parse::Parsed parts;
   AutocompleteInput::Parse(display_text, model_->GetDesiredTLD(),
@@ skipping 374 matching lines @@
 // prepended and ".com" appended.  This calls down to
 // AutocompleteEditModel::OnControlKeyChanged() so that it can change
 // the popup to reflect this.  See autocomplete_edit.cc
 // OnControlKeyChanged() and OnAfterPossibleChange().
 - (void)control:(NSControl*)control flagsChanged:(NSEvent*)theEvent {
   BOOL controlFlag = ([theEvent modifierFlags]&NSControlKeyMask) != 0;
   edit_view_->OnControlKeyChanged(controlFlag);
 }
 
 @end