"Bootstrap" a toolkit-views Typography spec.

chrome/browser/ui/views/harmony/layout_delegate.cc

 // Copyright 2016 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.
 
 #include "chrome/browser/ui/views/harmony/layout_delegate.h"
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "chrome/browser/ui/views/chrome_views_delegate.h"
+#include "chrome/browser/ui/views/harmony/chrome_typography.h"
 #include "chrome/browser/ui/views/harmony/harmony_layout_delegate.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/views/layout/layout_constants.h"
 
 static base::LazyInstance<LayoutDelegate>::DestructorAtExit layout_delegate_ =
     LAZY_INSTANCE_INITIALIZER;
 
 // static
 LayoutDelegate* LayoutDelegate::Get() {
   return ui::MaterialDesignController::IsSecondaryUiMaterial()
@@ skipping 57 matching lines @@
   return true;
 }
 
 bool LayoutDelegate::IsHarmonyMode() const {
   return false;
 }
 
 int LayoutDelegate::GetDialogPreferredWidth(DialogWidth width) const {
   return 0;
 }
+
+const views::TypographyProvider& LayoutDelegate::GetTypographyProvider() const {
+  // HarmonyLayoutDelegate inherits from |this| and shouldn't inherit a
+  // LegacyTypographyProvider.

[Peter Kasting, 2017/03/17 02:26:00]

I'm confused by this comment.  HarmonyLayoutDelegate isn't overriding this
method in this patch.  What does "shouldn't inherit" mean here, then?

[tapted, 2017/03/17 10:33:10]

Sorry - yes, this was pretty unclear (static here feels weird, so I wanted to
comment). To make it a data member, HarmonyLayoutDelegate would inherit it,
which isn't right. But, with a static, when HarmonyLayoutDelegate *does*
override this method then this will never get created. Updated the comment.

  // This is not a data member because then HarmonyLayoutDelegate would inherit
  // it, even when it provides its own.

(but I'm open to other suggestions too :)

[Peter Kasting, 2017/03/17 20:59:39]

Ah.  That's fine if you want.  I think the comment assumes that the reader is
wondering "why wasn't this a nonstatic data member?".  Whereas I figured a
static local was the sane thing to do, so it was answering a question I didn't
have, so I was confused.

+  CR_DEFINE_STATIC_LOCAL(LegacyTypographyProvider, legacy_provider, ());
+  return legacy_provider;
+}