cros: Temporary fix to show ProxyBasicAuth prompt on views-login.

When the basic auth widget appears, it is fetching the parent widget using
WebContentsModalDialogHost::GetHostView. CaptivePortalDialogDelegate overrides
this to return the captive portal widget, which is hidden. Thus, the auth widget
is also hidden because its parent widget is hidden.

I believe the correct long-term fix is to not share a WebContents instance
bewteen OoobeUIDialogDelegate and CaptivePortalDialogDelegate. However, that
seems like a much riskier change.

Add a hacky check to return the widget for OoobeUIDialogDelegate if the
CaptivePortalDialogDelegate widget is currently hidden.

Bug: 890976
Change-Id: I0d974449d7eb425a8bb99dcc8d34eb6582c097e7
Reviewed-on: https://chromium-review.googlesource.com/c/1263040Reviewed-by: Quan Nguyen <qnnguyen@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596865}

chrome/browser/chromeos/login/ui/oobe_ui_dialog_delegate.cc

@@ -67,8 +67,9 @@ class CaptivePortalDialogDelegate
       public ChromeWebModalDialogManagerDelegate,
       public web_modal::WebContentsModalDialogHost {
  public:
-  explicit CaptivePortalDialogDelegate(content::WebContents* web_contents)
-      : web_contents_(web_contents) {
+  explicit CaptivePortalDialogDelegate(views::WebDialogView* host_dialog_view)
+      : host_view_(host_dialog_view),
+        web_contents_(host_dialog_view->web_contents()) {
     view_ = new views::WebDialogView(ProfileHelper::GetSigninProfile(), this,
                                      new ChromeWebContentsHandler);
     view_->SetVisible(false);
@@ -106,7 +107,10 @@ class CaptivePortalDialogDelegate
 
   // web_modal::WebContentsModalDialogHost:
   gfx::NativeView GetHostView() const override {
-    return widget_->GetNativeWindow();
+    if (widget_->IsVisible())
+      return widget_->GetNativeWindow();
+    else
+      return host_view_->GetWidget()->GetNativeWindow();
   }
 
   gfx::Point GetDialogPosition(const gfx::Size& size) override {
@@ -160,6 +164,7 @@ class CaptivePortalDialogDelegate
  private:
   views::Widget* widget_ = nullptr;
   views::WebDialogView* view_ = nullptr;
+  views::WebDialogView* host_view_ = nullptr;
   content::WebContents* web_contents_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(CaptivePortalDialogDelegate);
@@ -198,8 +203,7 @@ OobeUIDialogDelegate::OobeUIDialogDelegate(
 
   dialog_view_->web_contents()->SetDelegate(this);
 
-  captive_portal_delegate_ =
-      new CaptivePortalDialogDelegate(dialog_view_->web_contents());
+  captive_portal_delegate_ = new CaptivePortalDialogDelegate(dialog_view_);
 
   GetOobeUI()->GetErrorScreen()->MaybeInitCaptivePortalWindowProxy(
       dialog_view_->web_contents());