Extract colors from wallpaper and dynamically update login screen overlay

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

Index: chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
index 168c632f511766e5a7433c295925a78d8a9b1ad1..c058715e9bc1efe1db04f23d0b4bc1baa97ce26f 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
@@ -1017,6 +1017,17 @@ void SigninScreenHandler::OnCurrentScreenChanged(OobeScreen current_screen,
   }
 }
 
+void SigninScreenHandler::OnColorCalculationComplete() {
+  std::string dm_color;
+  std::string scroll_color;
+  std::string background_color;
+  WallpaperManager::Get()->getLoginOverlayColors(&dm_color, &scroll_color,
+                                                 &background_color);
+  WallpaperManager::Get()->SetLoginOverlayCalculatorObserver(nullptr);
+  CallJS("login.AccountPickerScreen.setOverlayColors", dm_color, scroll_color,
+         background_color);
+}
+
 void SigninScreenHandler::ClearAndEnablePassword() {
   core_oobe_view_->ResetSignInUI(false);
 }
@@ -1275,8 +1286,8 @@ void SigninScreenHandler::HandleShutdownSystem() {
 }
 
 void SigninScreenHandler::HandleLoadWallpaper(const AccountId& account_id) {
-  if (delegate_)
-    delegate_->LoadWallpaper(account_id);
+  WallpaperManager::Get()->SetLoginOverlayCalculatorObserver(this);
+  WallpaperManager::Get()->SetUserWallpaperDelayed(account_id);
 }
 
 void SigninScreenHandler::HandleRebootSystem() {
@@ -1495,6 +1506,7 @@ void SigninScreenHandler::HandleFocusPod(const AccountId& account_id) {
   } else {
     SetUserInputMethod(account_id.GetUserEmail(), ime_state_.get());
     SetKeyboardSettings(account_id);
+    WallpaperManager::Get()->SetLoginOverlayCalculatorObserver(this);
     WallpaperManager::Get()->SetUserWallpaperDelayed(account_id);
 
     bool use_24hour_clock = false;