Show "displays" section in the options page even for 1 display. It happens in case of mirroring.

chrome/browser/ui/webui/options2/chromeos/display_options_handler.cc

 // 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.
 
 #include "chrome/browser/ui/webui/options2/chromeos/display_options_handler.h"
 
 #include <string>
 
 #include "ash/display/display_controller.h"
 #include "ash/shell.h"
@@ skipping 63 matching lines @@
   UpdateDisplaySectionVisibility();
   SendDisplayInfo();
 }
 
 void DisplayOptionsHandler::OnDisplayRemoved(const gfx::Display& old_display) {
   UpdateDisplaySectionVisibility();
   SendDisplayInfo();
 }
 
 void DisplayOptionsHandler::UpdateDisplaySectionVisibility() {
-  aura::DisplayManager* display_manager =
-      aura::Env::GetInstance()->display_manager();
   chromeos::State output_state =
       ash::Shell::GetInstance()->output_configurator()->output_state();
   base::FundamentalValue show_options(
       DisplayController::IsExtendedDesktopEnabled() &&
-      display_manager->GetNumDisplays() > 1 &&
       output_state != chromeos::STATE_INVALID &&
       output_state != chromeos::STATE_HEADLESS &&
       output_state != chromeos::STATE_SINGLE);

[oshima, 2012/07/25 07:53:41]

I think it's easier to read/follow if you list valid cases like

output_state == chromeos::STATE_DUAL_MIRROR || ..

rather than opposite.

[Jun Mukai, 2012/07/25 08:14:43]

Are there no chances to add a new state even when we want to support >2
displays?  I was just afraid to forget keeping the consistency in that case.

[oshima, 2012/07/25 13:03:37]

Existing code can break when state enum changes too. How about adding
int OutputConfigurator::GetNumPhisicalDisplays() and use it instead?

[Jun Mukai, 2012/07/25 14:44:42]

Can we do that in another CL?  That doesn't sound so relevant to this CL
description.

   web_ui()->CallJavascriptFunction(
       "options.BrowserOptions.showDisplayOptions", show_options);
 }
 
 void DisplayOptionsHandler::SendDisplayInfo() {
   aura::DisplayManager* display_manager =
       aura::Env::GetInstance()->display_manager();
   chromeos::OutputConfigurator* output_configurator =
       ash::Shell::GetInstance()->output_configurator();
   base::FundamentalValue mirroring(
@@ skipping 48 matching lines @@
   DCHECK_LE(DisplayController::TOP, layout);
   DCHECK_GE(DisplayController::LEFT, layout);
 
   ash::Shell::GetInstance()->display_controller()->SetSecondaryDisplayLayout(
       static_cast<DisplayController::SecondaryDisplayLayout>(layout));
   SendDisplayInfo();
 }
 
 }  // namespace options2
 }  // namespace chromeos