Allow dialogs to use a custom View as their title.

ui/views/window/dialog_delegate.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_
 #define UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "ui/accessibility/ax_enums.h"
 #include "ui/base/models/dialog_model.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
 
 namespace views {
 
 class DialogClientView;
 class LabelButton;
+class StyledLabel;
 
 ///////////////////////////////////////////////////////////////////////////////
 //
 // DialogDelegate
 //
 //  DialogDelegate is an interface implemented by objects that wish to show a
 //  dialog box Window. The window that is displayed uses this interface to
 //  determine how it should be displayed and notify the delegate object of
 //  certain events.
 //
@@ skipping 10 matching lines @@
                                     gfx::NativeView parent);
 
   // Returns the dialog widget InitParams for a given |context| or |parent|.
   // If |bounds| is not empty, used to initially place the dialog, otherwise
   // a default location is used.
   static Widget::InitParams GetDialogWidgetInitParams(WidgetDelegate* delegate,
                                                       gfx::NativeWindow context,
                                                       gfx::NativeView parent,
                                                       const gfx::Rect& bounds);
 
+  // Returns a StyledLabel to use as the title of the bubble. By default returns
+  // nullptr to indicate the default title should be used instead.
+  virtual StyledLabel* CreateTitleView();

[sky, 2017/06/06 23:55:10]

One concern I have with adding this here is that not all dialogs end up in this
code path. For example, the TaskManager won't hit this code path. And you're
only changing BubbleFrameView. I think it's best to isolate this in bubble code,
and in particular BubbleFrameView. I also think it would be good to avoid
recreating the titleview every time. How about BubbleDialogDelegate gets a
SetTitleView(). If called it's assumed the titleview updates itself as
appropriate. SetTitleView() would take a View*, not a StyledLabel.

[Bret, 2017/06/07 00:37:46]

TaskManagerView is a DialogDelegateView, so I think it will hit this code path.
As far as I know the only BubbleFrameView widget that don't use DialogDelegate
is ScreenCaptureNotificationUIViews, and it doesn't have a title.

I'm with you on not wanting to create a new title each UpdateWindowTitle call,
but I'm not following your suggestion. I could plumb through an update call,
after UpdateWindowTitle calls SetText, to the DialogDelegate so it can call
AddStyleRange if it wants to... is that what you mean? Also I don't think it can
ever be a generic View, because of AddStyleRange on the delegate end and
SetBaseFontList/SizeToFit on the BubbleFrameView end.

[sky, 2017/06/07 15:59:40]

The new function you are adding is only called from BubbleFrameView.
TaskManagerView is a DialogDelegate, but it won't create BubbleFrameView and
have this called.
I'm suggesting you add a SetTitleView() function to BubbleFrameView. If
SetTitleView() is called that's the View that is used as the title_ for layout
and size calculation. So, roughly something like:

  SetTitleView(View* title_view) {
    default default_title_view_;
    default_title_view_ = nullptr;
    title_ = title_view;
  }

  // Default title to use for the bubble. If SetTitleView() is called this is
null.
  Label* default_title_;
  // Client specified view to render the title.
  View* explicitly_set_title_ = nullptr;

Most places in BubbleFrameView that access title_ would instead use a title()
function:

  View* title() { return explicitly_set_title_ ? explicitly_set_title_ :
default_title_; }

UpdateWindowTitle becomes:

  void UpdateWindowTitle() {
    if (default_title_)
      default_title_->SetText(...);
    // else case, assume client that supplied title view updates it.
  }

Make sense?

The password code has access to the BubbleFrameView by way of
GetBubbleFrameView(), so early on the password code creates the styled label and
calls GetBubbleFrameView()->SetTitleView(styled_label).

Does that make sense?

[Bret, 2017/06/07 20:15:41]

Okay you're right, that's kind of subtle. It doesn't have a title label anyway,
but I understand your point about it being weird that it could override this
function and nothing would happen.
Okay, your idea makes sense. I don't think the delegate gets notified when the
title needs updating right now, so I'd have to add that. The other thing to
resolve is SetTitleFontList... I wonder if I can just move its usages into
custom Label views with my new mechanism.

+
   // Override this function to display an extra view adjacent to the buttons.
   // Overrides may construct the view; this will only be called once per dialog.
   virtual View* CreateExtraView();
 
   // Override this function to adjust the padding between the extra view and
   // the confirm/cancel buttons. Note that if there are no buttons, this will
   // not be used.
   // If a custom padding should be used, returns true and populates |padding|.
   virtual bool GetExtraViewPadding(int* padding);
 
@@ skipping 92 matching lines @@
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DialogDelegateView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_DIALOG_DELEGATE_H_