[Mac] Preserve original selection when suggesting completions with diacritics

chrome/browser/ui/cocoa/omnibox/omnibox_view_mac_browsertest.mm

 // Copyright (c) 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.
 
 #import "chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.h"
 
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
@@ skipping 76 matching lines @@
   GetOmnibox()->CopyToPasteboard(pasteboard->get());
 
   // Check that the custom Pboard type is no longer present.
   EXPECT_FALSE([pasteboard->get()
       stringForType:ui::ClipboardUtil::UTIForPasteboardType(pboard_type)]);
 
   // Check that the contents of the omnibox were copied to the clipboard.
   pasteboard_string = [pasteboard->get() stringForType:NSPasteboardTypeString];
   EXPECT_EQ(text, pasteboard_string.UTF8String);
 }
+
+// Verify that copying text from the omnibox into the pasteboard works with
+// a selection that begins on a combining character.
+IN_PROC_BROWSER_TEST_F(OmniboxViewMacBrowserTest, CopyToPasteboardDiacritic) {

[lgrey, 2016/10/13 21:03:56]

This test is basically a proxy for testing GetSelectedRange which is private

+  base::string16 text = base::UTF8ToUTF16("สวัสดี");
+
+  scoped_refptr<ui::UniquePasteboard> pasteboard = new ui::UniquePasteboard;
+  [[GetOmnibox()->field() currentEditor]
+      setString:base::SysUTF16ToNSString(text)];
+  [[GetOmnibox()->field() currentEditor]
+      setSelectedRange:NSMakeRange(2, text.size() - 2)];
+
+  GetOmnibox()->model()->SetUserText(text);
+  GetOmnibox()->CopyToPasteboard(pasteboard->get());
+
+  NSString* pasteboard_string =
+      [pasteboard->get() stringForType:NSPasteboardTypeString];
+  EXPECT_EQ(text.substr(2, 4), base::SysNSStringToUTF16(pasteboard_string));
+}