Unify desktop Linux and Chrome OS font rendering params.

ui/gfx/platform_font_pango.cc

Index: ui/gfx/platform_font_pango.cc
diff --git a/ui/gfx/platform_font_pango.cc b/ui/gfx/platform_font_pango.cc
index 2c89ac5baa83d035803e66bf05c0bf492fd48ca3..fdae6ae0604e71c051cac807461264e2b927c927 100644
--- a/ui/gfx/platform_font_pango.cc
+++ b/ui/gfx/platform_font_pango.cc
@@ -48,19 +48,24 @@ std::string* PlatformFontPango::default_font_description_ = NULL;
 
 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(