Fix omnibox flickering on macOS Sierra.

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

 // Copyright (c) 2011 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/location_bar/autocomplete_text_field_editor.h"
 
 #include "base/mac/sdk_forward_declarations.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/app/chrome_command_ids.h"  // IDC_*
@@ skipping 471 matching lines @@
   if (observer)
     observer->OnBeforeChange();
 
   [super interpretKeyEvents:eventArray];
 
   if (textChangedByKeyEvents_ && observer)
     observer->OnDidChange();
 
   DCHECK(interpretingKeyEvents_);
   interpretingKeyEvents_ = NO;
+
+  // -[NSTextView interpretKeyEvents:] invalidates the existing layout.
+  //
+  // observer->OnDidChange() calls OmniboxViewMac::ApplyTextStyle, which
+  // invalidates the existing layout again, but in a slightly different way.
+  // Details unclear.
+  //
+  // On older versions of macOS, this results in a single call to -[NSTextView
+  // drawRect:] on the next frame, which paints the correct contents.
+  //
+  // On macOS 10.12 dp4, for unknown reasons, this causes two calls to
+  // -[NSTextView drawRect:] across two(!) frames. The first call to
+  // -[NSTextView drawRect:] draws no text, which causes a flicker in the
+  // omnibox. Forcing a layout ensures that drawRect: is only called once, and
+  // is drawn with the correct contents.
+  // https://crbug.com/634318.
+  [self.layoutManager
+      ensureLayoutForCharacterRange:NSMakeRange(0, self.textStorage.length)];
 }
 
 - (BOOL)shouldChangeTextInRange:(NSRange)affectedCharRange
               replacementString:(NSString *)replacementString {
   BOOL ret = [super shouldChangeTextInRange:affectedCharRange
                           replacementString:replacementString];
 
   if (ret && !interpretingKeyEvents_) {
     AutocompleteTextFieldObserver* observer = [self observer];
     if (observer)
@@ skipping 106 matching lines @@
   if (!ui::MaterialDesignController::IsModeMaterial()) {
     return;
   }
   [self updateColorsToMatchTheme];
 }
 
 - (void)windowDidChangeActive {
 }
 
 @end