cros: HTML fixes needed to reinitializing an existing lock WebUI.

See https://codereview.chromium.org/2512473004/ for additional context.

BUG=669638
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2555453003
Cr-Commit-Position: refs/heads/master@{#437964}

chrome/browser/chromeos/login/screens/user_selection_screen.cc

@@ -269,6 +269,13 @@ bool UserSelectionScreen::ShouldForceOnlineSignIn(
 
 void UserSelectionScreen::SetHandler(LoginDisplayWebUIHandler* handler) {
   handler_ = handler;
+
+  if (handler_) {
+    // Forcibly refresh all of the user images, as the |handler_| instance may
+    // have been reused.
+    for (user_manager::User* user : users_)
+      handler_->OnUserImageChanged(*user);
+  }
 }
 
 void UserSelectionScreen::SetView(UserBoardView* view) {

chrome/browser/chromeos/login/signin_screen_controller.h

@@ -23,6 +23,10 @@ class OobeUI;
 
 // Class that manages control flow between wizard screens. Wizard controller
 // interacts with screen controllers to move the user between screens.
+//
+// This class is allocated when the signin or lock screen is actually visible to
+// the user. It is a 'per-session' class; SignInScreenHandler, in comparsion, is
+// tied to the WebContents lifetime and therefore may live beyond this class.
 class SignInScreenController : public user_manager::RemoveUserDelegate,
                                public content::NotificationObserver {
  public:

chrome/browser/resources/chromeos/login/lock.js

@@ -66,6 +66,39 @@ cr.define('cr.ui.Oobe', function() {
       chrome.send('screenStateInitialize');
     },
 
+    /**
+     * Notification from the host that the PIN keyboard will be used in the
+     * lock session so it should also get preloaded.
+     */
+    preloadPinKeyboard: function() {
+      showPinKeyboardAsync();
+    },
+
+    /**
+     * Called when a preloaded webview (this) instance is being reused to
+     * display a new lock screen session. This will also be called when a
+     * lock screen has been preloaded and is being displayed for the first
+     * time.
+     */
+    reload: function() {
+      // Sending accountPickerReady displays the webui. Wait for the next
+      // animation frame so the user does not see any state from the previous
+      // instance.
+      requestAnimationFrame(function() {
+        chrome.send('accountPickerReady');
+      });
+    },
+
+    /**
+     * Called when the lock screen has been dismissed but this webview will stay
+     * in memory. The webview will be reused when Oobe.reload() is called.
+     */
+    teardown: function() {
+      // The PIN keyboard will disable the virtual keyboard. Make sure to
+      // revert the force disable when hiding the lock screen.
+      chrome.send('setForceDisableVirtualKeyboard', [false]);
+    },
+
     // Dummy Oobe functions not present with stripped login UI.
     initializeA11yMenu: function(e) {},
     handleAccessibilityLinkClick: function(e) {},

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc

@@ -894,6 +894,21 @@ void SigninScreenHandler::ReloadGaia(bool force_reload) {
 }
 
 void SigninScreenHandler::Initialize() {
+  // Preload PIN keyboard if any of the users can authenticate via PIN.
+  if (user_manager::UserManager::IsInitialized()) {
+    for (user_manager::User* user :
+         user_manager::UserManager::Get()->GetLoggedInUsers()) {
+
+      chromeos::PinStorage* pin_storage =
+          chromeos::PinStorageFactory::GetForUser(user);
+      if (pin_storage && pin_storage->IsPinAuthenticationAvailable()) {
+        CallJS("cr.ui.Oobe.preloadPinKeyboard");
+        break;
+      }
+    }
+  }
+
+  // |delegate_| is null when we are preloading the lock screen.
   if (delegate_ && show_on_init_) {
     show_on_init_ = false;
     ShowImpl();

ui/login/account_picker/screen_account_picker.js

@@ -266,6 +266,14 @@ login.createScreen('AccountPickerScreen', 'account-picker', function() {
      * @param {array} users Array of user instances.
      */
     initializePinKeyboardStateForUsers_: function(users) {
+      // It is possible that the PIN keyboard HTML has already been loaded. If
+      // that is the case, we want to show the user pods with the PIN keyboard
+      // immediately without running the PIN show/hide effect.
+      document.body.classList.add('disable-pin-animation');
+      setTimeout(function() {
+        document.body.classList.remove('disable-pin-animation');
+      });
+
       for (var i = 0; i < users.length; ++i) {
         var user = users[i];
         if (user.showPin) {

ui/login/account_picker/user_pod_row.css

@@ -54,6 +54,10 @@ pin-keyboard {
   top: -87px !important;
 }
 
+.disable-pin-animation .pod.pin-enabled {
+  transition: none;
+}
+
 .pod .pin-container {
   height: 204px;
   position: absolute;

ui/login/screen_container.css

@@ -34,6 +34,10 @@
                          checked to determine if loaded. */
 }
 
+.disable-pin-animation .pin-container {
+  transition: none;
+}
+
 #scroll-container {
   bottom: 0;        /* Allows content overlap with control bar. */
   left: 0;