[Mac] Polish the search engine manager

chrome/browser/cocoa/edit_search_engine_cocoa_controller.mm

Index: chrome/browser/cocoa/edit_search_engine_cocoa_controller.mm
diff --git a/chrome/browser/cocoa/edit_search_engine_cocoa_controller.mm b/chrome/browser/cocoa/edit_search_engine_cocoa_controller.mm
index 00e4913ec5a6f1edf3ab21ce9e2a1a64996539ae..d3e213151027e8ba882201512a6aad1b4ccf6b2e 100644
--- a/chrome/browser/cocoa/edit_search_engine_cocoa_controller.mm
+++ b/chrome/browser/cocoa/edit_search_engine_cocoa_controller.mm
@@ -102,8 +102,18 @@ void ShiftOriginY(NSView* view, CGFloat amount) {
   [self autorelease];
 }
 
+// Performs the logic of closing the window. If we are a sheet, then it ends the
+// modal session; otherwise, it closes the window.
+- (void)doClose {
+  if ([[self window] isSheet]) {
+    [NSApp endSheet:[self window]];
+  } else {
+    [[self window] close];
+  }
+}
+
 - (IBAction)cancel:(id)sender {
-  [[self window] close];
+  [self doClose];
 }
 
 - (IBAction)save:(id)sender {
@@ -112,7 +122,7 @@ void ShiftOriginY(NSView* view, CGFloat amount) {
   std::wstring keyword = base::SysNSStringToWide([keywordField_ stringValue]);
   std::wstring url = base::SysNSStringToWide([urlField_ stringValue]);
   controller_->AcceptAddOrEdit(title, keyword, url);
-  [[self window] close];
+  [self doClose];
 }
 
 // Delegate method for the text fields.