[linux] Allow font to use below 1.0f scale

chrome/browser/ui/libgtkui/gtk_ui.h

 // Copyright (c) 2013 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 CHROME_BROWSER_UI_LIBGTKUI_GTK_UI_H_
 #define CHROME_BROWSER_UI_LIBGTKUI_GTK_UI_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 87 matching lines @@
       views::WindowButtonOrderObserver* observer) override;
   bool UnityIsRunning() override;
   NonClientMiddleClickAction GetNonClientMiddleClickAction() override;
   void NotifyWindowManagerStartupComplete() override;
 
   // ui::TextEditKeybindingDelegate:
   bool MatchEvent(const ui::Event& event,
                   std::vector<ui::TextEditCommandAuraLinux>* commands) override;
 
   // ui::Views::LinuxUI:
-  void UpdateDeviceScaleFactor(float device_scale_factor) override;
+  void UpdateDeviceScaleFactor() override;
   float GetDeviceScaleFactor() const override;
 
  private:
   typedef std::map<int, SkColor> ColorMap;
   typedef std::map<int, color_utils::HSL> TintMap;
 
   // This method returns the colors webkit will use for the scrollbars. When no
   // colors are specified by the GTK+ theme, this function averages of the
   // thumb part and of the track colors.
   void SetScrollbarColors();
@@ skipping 74 matching lines @@
 
   // Whether we should lower the window on a middle click to the non client
   // area.
   NonClientMiddleClickAction middle_click_action_;
 
   // Used to override the native theme for a window. If no override is provided
   // or the callback returns NULL, Gtk2UI will default to a NativeThemeGtk2
   // instance.
   NativeThemeGetter native_theme_overrider_;
 
-  float device_scale_factor_;
+  float device_scale_factor_ = 1.0f;

[Evan Stade, 2016/11/03 16:38:03]

seems like we should init things in the same place (at least those that are
init'd with const expressions), either all in the ctor init list or all in this
file

I am ambivalent about which one and I dunno what the style guide has to say
about it, if anything.

[oshima, 2016/11/05 15:15:05]

I moved default_font_xxx to the header.

 
   DISALLOW_COPY_AND_ASSIGN(Gtk2UI);
 };
 
 }  // namespace libgtkui
 
 // Access point to the GTK2 desktop system. This should be the only symbol that
 // is exported in the library; everything else should be used through the
 // interface, because eventually this .so will be loaded through dlopen at
 // runtime so our main binary can conditionally load GTK2 or GTK3 or EFL or
 // QT or whatever.
 LIBGTKUI_EXPORT views::LinuxUI* BuildGtk2UI();
 
 #endif  // CHROME_BROWSER_UI_LIBGTKUI_GTK_UI_H_