Unify desktop Linux and Chrome OS font rendering params.

ui/gfx/platform_font_pango.cc

 // 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.
 
 #include "ui/gfx/platform_font_pango.h"
 
 #include <fontconfig/fontconfig.h>
 #include <pango/pango.h>
 
 #include <algorithm>
@@ skipping 30 matching lines @@
 #if defined(OS_CHROMEOS)
 // static
 std::string* PlatformFontPango::default_font_description_ = NULL;
 #endif
 
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformFontPango, public:
 
 PlatformFontPango::PlatformFontPango() {
   if (!default_font_) {
-    std::string desc_string;
+    scoped_ptr<ScopedPangoFontDescription> desc;

[msw, 2014/07/18 19:14:44]

nit: |description| shouldn't cause any extra wrapping, afaict.

[Daniel Erat, 2014/07/18 19:39:09]

Done.

+    const gfx::LinuxFontDelegate* delegate = gfx::LinuxFontDelegate::instance();
+    if (delegate)
+      desc = delegate->GetDefaultPangoFontDescription();
+
+    if (!desc.get()) {
+      std::string desc_string;
 #if defined(OS_CHROMEOS)
-    // Font name must have been provided by way of SetDefaultFontDescription().
-    CHECK(default_font_description_);
-    desc_string = *default_font_description_;
+      CHECK(default_font_description_);

[msw, 2014/07/18 19:14:44]

ChromeOS uses InitDefaultFontList() to set a specific
|default_font_description_| that should be used here instead of (or before
falling back upon) delegate->GetDefaultPangoFontDescription()?

Perhaps that code could be changed [later] to only set the default value on
gfx::FontList or gfx::PlatformFontPango (and remove the default value member
from the other).

[Daniel Erat, 2014/07/18 19:39:09]

chrome os doesn't use a LinuxFontDelegate (although i'm wondering if it should,
at some point). i've reordered the code to make this clearer, but let me know if
you preferred it the previous way. note that i'm still checking the delegate on
chrome os in font_render_params_linux.cc, just to avoid ifdefs there.

ui/base/resource/resource_bundle.cc has the following:

  // TODO(yukishiino): Remove SetDefaultFontDescription() once the migration to
  // the font list is done.  We will no longer need SetDefaultFontDescription()
  // after every client gets started using a FontList instead of a Font.

i'm not sure what the status of that is, though.

[msw, 2014/07/18 19:59:46]

Hmm, I think the latest patch set is a bit safer for now, but obviously isn't
the long term ideal solution.

+      desc_string = *default_font_description_;
 #else
-    const gfx::LinuxFontDelegate* delegate = gfx::LinuxFontDelegate::instance();
-    desc_string = delegate ? delegate->GetDefaultFontDescription() : "sans 10";
+      desc_string = "sans 10";
 #endif
+      desc.reset(new ScopedPangoFontDescription(
+          pango_font_description_from_string(desc_string.c_str())));
+    }
 
-    ScopedPangoFontDescription desc(
-        pango_font_description_from_string(desc_string.c_str()));
-    default_font_ = new Font(desc.get());
+    default_font_ = new Font(desc->get());
   }
 
   InitFromPlatformFont(
       static_cast<PlatformFontPango*>(default_font_->platform_font()));
 }
 
 PlatformFontPango::PlatformFontPango(NativeFont native_font) {
   const int pango_size =
       pango_font_description_get_size(native_font) / PANGO_SCALE;
   const bool pango_using_pixels =
@@ skipping 292 matching lines @@
   return new PlatformFontPango(native_font);
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontPango(font_name, font_size);
 }
 
 }  // namespace gfx