[ChromeOS] Expose keyboard remapping to signin screen.

chrome/browser/chromeos/events/event_rewriter.cc

 // Copyright 2014 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/chromeos/events/event_rewriter.h"
 
 #include <stddef.h>
 
 #include <vector>
 
 #include "ash/common/wm/window_state.h"
 #include "ash/sticky_keys/sticky_keys_controller.h"
 #include "ash/wm/window_util.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/sys_info.h"
 #include "chrome/browser/chromeos/login/ui/login_display_host.h"
 #include "chrome/browser/extensions/extension_commands_global_registry.h"
 #include "chrome/browser/profiles/profile_manager.h"
+#include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
+#include "chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h"
 #include "chrome/common/pref_names.h"
 #include "chromeos/chromeos_switches.h"
 #include "components/prefs/pref_service.h"
+#include "components/user_manager/known_user.h"
 #include "components/user_manager/user_manager.h"
 #include "ui/base/ime/chromeos/ime_keyboard.h"
 #include "ui/base/ime/chromeos/input_method_manager.h"
 #include "ui/events/devices/input_device_manager.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/dom/dom_code.h"
 #include "ui/events/keycodes/dom/dom_key.h"
 #include "ui/events/keycodes/dom/keycode_converter.h"
 #include "ui/events/keycodes/keyboard_code_conversion.h"
@@ skipping 89 matching lines @@
      {ui::EF_NONE, ui::DomCode::F15, ui::DomKey::F15, ui::VKEY_F15}}};
 
 const ModifierRemapping* kModifierRemappingCtrl = &kModifierRemappings[0];
 const ModifierRemapping* kModifierRemappingNeoMod3 = &kModifierRemappings[1];
 
 // Gets a remapped key for |pref_name| key. For example, to find out which
 // key Search is currently remapped to, call the function with
 // prefs::kLanguageRemapSearchKeyTo.
 const ModifierRemapping* GetRemappedKey(const std::string& pref_name,
                                         const PrefService& pref_service) {
-  if (!pref_service.FindPreference(pref_name.c_str()))
-    return NULL;  // The |pref_name| hasn't been registered. On login screen?
-  const int value = pref_service.GetInteger(pref_name.c_str());
+  int value = -1;
+  // If we're at the login screen, try to get the pref from the global prefs
+  // dictionary.
+  if (LoginDisplayHost::default_host()) {
+    const AccountId focused_account_id = LoginDisplayHost::default_host()
+                                             ->GetOobeUI()
+                                             ->signin_screen_handler()
+                                             ->focused_pod_account_id();
+    if (!focused_account_id.empty()) {

[xiyuan, 2017/02/22 17:40:18]

nit: empty() -> is_valid()

+      user_manager::known_user::GetIntegerPref(focused_account_id, pref_name,
+                                               &value);

[Alexander Alekseev, 2017/02/22 10:51:50]

I am not an owner of this file, but it seems to me that this is too
login-specific for event rewriter.

Did you consider moving these new lines to:
bool SigninScreenHandler::GetKeyboardRemappingValue(
    const std::string& pref_name, 
    int* value);
?

It could return true if there is a focused pod and a preference for focused
user.

Then, it will become:

if (!LoginDisplayHost::default_host() ||
    !LoginDisplayHost::default_host()>GetOobeUI()
        ->signin_screen_handler()
        ->GetKeyboardRemappingValue(pref_name, &value)) {

  if (!pref_service.FindPreference(pref_name.c_str()))
    return NULL;  // The |pref_name| hasn't been registered.

  const int value = pref_service.GetInteger(pref_name.c_str());
}

for(...) {
}

return nullptr;
}

[xdai1, 2017/02/22 18:36:16]

Done.

+    }
+  }
+
+  if (value == -1) {
+    if (pref_service.FindPreference(pref_name))
+      value = pref_service.GetInteger(pref_name);
+    else
+      return nullptr;
+  }
+
   for (size_t i = 0; i < arraysize(kModifierRemappings); ++i) {
     if (value == kModifierRemappings[i].remap_to)
       return &kModifierRemappings[i];
   }
-  return NULL;
+  return nullptr;
 }
 
 bool HasDiamondKey() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       chromeos::switches::kHasChromeOSDiamondKey);
 }
 
 bool IsISOLevel5ShiftUsedByCurrentInputMethod() {
   // Since both German Neo2 XKB layout and Caps Lock depend on Mod3Mask,
   // it's not possible to make both features work. For now, we don't remap
@@ skipping 1002 matching lines @@
   for (const auto& keyboard : keyboard_devices) {
     if (keyboard.id == device_id) {
       return KeyboardDeviceAddedInternal(
           keyboard.id, keyboard.name, keyboard.vendor_id, keyboard.product_id);
     }
   }
   return kDeviceUnknown;
 }
 
 }  // namespace chromeos