[Mac] Preserve original selection when suggesting completions with diacritics

chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_editor_unittest.mm

Index: chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_editor_unittest.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_editor_unittest.mm b/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_editor_unittest.mm
index 3f1a19a7a5ac49960ea0bcf25181d006f52913a7..e0e4866c4417e3963709934d1fd4b1a321131f4a 100644
--- a/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_editor_unittest.mm
+++ b/chrome/browser/ui/cocoa/location_bar/autocomplete_text_field_editor_unittest.mm
@@ -204,6 +204,42 @@ TEST_F(AutocompleteTextFieldEditorTest, GrayText) {
   [editor_ display];
 }
 
+// Test that the text view still responds to the private method
+// _userReplaceRange:withString: in case it's removed in future SDKs.
+TEST_F(AutocompleteTextFieldEditorTest, RespondsToUserReplaceRange) {
+  SEL selector = @selector(_userReplaceRange:withString:);
+  EXPECT_TRUE([editor_ respondsToSelector:selector]);
+}
+
+// Test that deleting with a selection that begins just before a
+// combining character works as expected.
+TEST_F(AutocompleteTextFieldEditorTest, DeletesOriginalRange) {
+  [field_ setStringValue:@"สวัสดี"];
+  [editor_ setSelectedRange:NSMakeRange(2, 4)];
+  [editor_ deleteBackward:nil];
+
+  EXPECT_TRUE([[editor_ string] isEqualToString:@"สว"]);
+}
+
+// Test that inserting text on top of a selection that begins just
+// before a combining character works as expected.
+TEST_F(AutocompleteTextFieldEditorTest, InsertTextUsesOriginalRange) {
+  [field_ setStringValue:@"สวัสดี"];
+  [editor_ setSelectedRange:NSMakeRange(2, 4)];
+  [editor_ insertText:@"น"];
+
+  EXPECT_TRUE([[editor_ string] isEqualToString:@"สวน"]);
+}
+
+// Test that |selectedRange| returns original range.
+TEST_F(AutocompleteTextFieldEditorTest, SelectedRangeReturnsOriginalRange) {
+  [field_ setStringValue:@"สวัสดี"];
+  NSRange range = NSMakeRange(2, 4);
+  [editor_ setSelectedRange:range];
+
+  EXPECT_TRUE(NSEqualRanges([editor_ selectedRange], range);
+}
+
 // Test that -paste: is correctly delegated to the observer.
 TEST_F(AutocompleteTextFieldEditorObserverTest, Paste) {
   EXPECT_CALL(field_observer_, OnPaste());