Fix Chrome OS Account Manager welcome screens UI

Please check the attached bug for context.

The screen needs to be:
  - Frameless (no title bar or 'X' button).
  - Non-draggable.
to conform to other current Chrome OS welcome dialogs.

Bug: 968143
Change-Id: Idcd85d37aa1985dd02002674d47996b76f96cc68
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1642067Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Kush Sinha <sinhak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665868}

chrome/browser/resources/chromeos/account_manager_shared.css

@@ -36,6 +36,7 @@ a {
 
 #google-logo {
   height: 32px;
+  margin-top: 40px;
   width: 32px;
 }
 

chrome/browser/ui/webui/chromeos/account_manager_welcome_dialog.cc

@@ -14,6 +14,7 @@
 #include "chrome/common/webui_url_constants.h"
 #include "components/prefs/pref_service.h"
 #include "ui/aura/window.h"
+#include "ui/wm/core/shadow_types.h"
 #include "url/gurl.h"
 
 namespace chromeos {
@@ -63,6 +64,13 @@ bool AccountManagerWelcomeDialog::ShowIfRequired() {
   return true;
 }
 
+void AccountManagerWelcomeDialog::AdjustWidgetInitParams(
+    views::Widget::InitParams* params) {
+  params->type = views::Widget::InitParams::Type::TYPE_WINDOW_FRAMELESS;
+  params->shadow_type = views::Widget::InitParams::ShadowType::SHADOW_TYPE_DROP;
+  params->shadow_elevation = wm::kShadowElevationActiveWindow;
+}
+
 void AccountManagerWelcomeDialog::OnDialogClosed(
     const std::string& json_retval) {
   chrome::SettingsWindowManager::GetInstance()->ShowOSSettings(

chrome/browser/ui/webui/chromeos/account_manager_welcome_dialog.h

@@ -24,6 +24,7 @@ class AccountManagerWelcomeDialog : public SystemWebDialogDelegate {
   ~AccountManagerWelcomeDialog() override;
 
   // ui::SystemWebDialogDelegate overrides.
+  void AdjustWidgetInitParams(views::Widget::InitParams* params) override;
   void OnDialogClosed(const std::string& json_retval) override;
   void GetDialogSize(gfx::Size* size) const override;
   std::string GetDialogArgs() const override;

chrome/browser/ui/webui/chromeos/account_migration_welcome_dialog.cc

@@ -2,6 +2,8 @@
 // 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/chromeos/account_migration_welcome_dialog.h"
+
 #include <string>
 
 #include "base/json/json_writer.h"
@@ -9,13 +11,13 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/settings_window_manager_chromeos.h"
-#include "chrome/browser/ui/webui/chromeos/account_migration_welcome_dialog.h"
 #include "chrome/browser/ui/webui/chromeos/account_migration_welcome_ui.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/webui_url_constants.h"
 #include "components/prefs/pref_service.h"
 #include "net/base/url_util.h"
 #include "ui/aura/window.h"
+#include "ui/wm/core/shadow_types.h"
 
 namespace chromeos {
 
@@ -58,6 +60,13 @@ AccountMigrationWelcomeDialog* AccountMigrationWelcomeDialog::Show(
   return dialog;
 }
 
+void AccountMigrationWelcomeDialog::AdjustWidgetInitParams(
+    views::Widget::InitParams* params) {
+  params->type = views::Widget::InitParams::Type::TYPE_WINDOW_FRAMELESS;
+  params->shadow_type = views::Widget::InitParams::ShadowType::SHADOW_TYPE_DROP;
+  params->shadow_elevation = wm::kShadowElevationActiveWindow;
+}
+
 std::string AccountMigrationWelcomeDialog::GetUserEmail() const {
   return email_;
 }

chrome/browser/ui/webui/chromeos/account_migration_welcome_dialog.h

@@ -24,6 +24,7 @@ class AccountMigrationWelcomeDialog : public SystemWebDialogDelegate {
   ~AccountMigrationWelcomeDialog() override;
 
   // ui::SystemWebDialogDelegate overrides.
+  void AdjustWidgetInitParams(views::Widget::InitParams* params) override;
   void GetDialogSize(gfx::Size* size) const override;
   std::string GetDialogArgs() const override;
   bool ShouldShowDialogTitle() const override;