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 56 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> description;
 #if defined(OS_CHROMEOS)
-    // Font name must have been provided by way of SetDefaultFontDescription().
     CHECK(default_font_description_);
-    desc_string = *default_font_description_;
+    description.reset(new ScopedPangoFontDescription(
+        pango_font_description_from_string(
+            default_font_description_->c_str())));
 #else
     const gfx::LinuxFontDelegate* delegate = gfx::LinuxFontDelegate::instance();
-    desc_string = delegate ? delegate->GetDefaultFontDescription() : "sans 10";
+    if (delegate) {
+      description = delegate->GetDefaultPangoFontDescription();
+    } else {

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

Should this be a separate check like "if (!description.get()) ..." or something
to check if the underlying description from the LinuxFontDelegate is empty?
Perhaps it could also live outside the preprocessor blocks.

[Daniel Erat, 2014/07/18 20:26:52]

sure. i'd prefer to have the delegate only return non-NULL descriptions, but
pango_font_description_copy() returns NULL when passed a NULL parameter and i
can't tell whether it's possible for GtkLabel's style's font_desc to be NULL, so
it's safer to do what you suggest.

pango_font_description_from_string() only returns NULL if passed a NULL string,
so this shouldn't be necessary for the chrome os case, but it doesn't hurt to
run it there.

to make this a bit more readable, i've changed ScopePangoFontDescription() to
have a c'tor that takes a string and automatically converts it to a
PangoFontDescription, but let me know if that seems too tricky.

+      description.reset(new ScopedPangoFontDescription(
+          pango_font_description_from_string("sans 10")));
+    }
 #endif
-
-    ScopedPangoFontDescription desc(
-        pango_font_description_from_string(desc_string.c_str()));
-    default_font_ = new Font(desc.get());
+    default_font_ = new Font(description->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 272 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