Add --keyboard-usability-test flag and always show keyboard unless manually hide

chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc

 // Copyright (c) 2013 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/ash/ash_keyboard_controller_proxy.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/shell.h"
 #include "chrome/browser/extensions/extension_function_dispatcher.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ skipping 130 matching lines @@
 }
 
 void AshKeyboardControllerProxy::ShowKeyboardContainer(
     aura::Window* container) {
   // TODO(bshe): Implement logic to decide which root window should display
   // virtual keyboard. http://crbug.com/303429
   if (container->GetRootWindow() != ash::Shell::GetPrimaryRootWindow())
     NOTIMPLEMENTED();
 
   KeyboardControllerProxy::ShowKeyboardContainer(container);
-  gfx::Rect showing_area =
-      ash::DisplayController::GetPrimaryDisplay().work_area();
-  GetInputMethod()->GetTextInputClient()->EnsureCaretInRect(showing_area);
+  // GetTextInputClient may return NULL when keyboard-usability-test flag is
+  // set.
+  if (GetInputMethod()->GetTextInputClient()) {
+    gfx::Rect showing_area =
+        ash::DisplayController::GetPrimaryDisplay().work_area();
+    GetInputMethod()->GetTextInputClient()->EnsureCaretInRect(showing_area);
+  }
 }
 
 void AshKeyboardControllerProxy::SetUpdateInputType(ui::TextInputType type) {
   // TODO(bshe): Need to check the affected window's profile once multi-profile
   // is supported.
   Profile* profile = ProfileManager::GetDefaultProfile();
   extensions::EventRouter* router =
       extensions::ExtensionSystem::Get(profile)->event_router();
 
   if (!router->HasEventListener(
           virtual_keyboard_private::OnTextInputBoxFocused::kEventName)) {
     return;
   }
 
   scoped_ptr<base::ListValue> event_args(new base::ListValue());
   scoped_ptr<base::DictionaryValue> input_context(new base::DictionaryValue());
   input_context->SetString("type",
       Context::ToString(TextInputTypeToGeneratedInputTypeEnum(type)));
   event_args->Append(input_context.release());
 
   scoped_ptr<extensions::Event> event(new extensions::Event(
       virtual_keyboard_private::OnTextInputBoxFocused::kEventName,
       event_args.Pass()));
   event->restrict_to_profile = profile;
   router->DispatchEventToExtension(kVirtualKeyboardExtensionID, event.Pass());
 }