[linux] Allow font to use below 1.0f scale

chrome/browser/ui/libgtk2ui/gtk2_ui.h

Index: chrome/browser/ui/libgtk2ui/gtk2_ui.h
diff --git a/chrome/browser/ui/libgtk2ui/gtk2_ui.h b/chrome/browser/ui/libgtk2ui/gtk2_ui.h
index e883e658594795a1dd8a390ef7624b9160c9a5fb..5f4b67c776342381092e9166fc56cc536105546e 100644
--- a/chrome/browser/ui/libgtk2ui/gtk2_ui.h
+++ b/chrome/browser/ui/libgtk2ui/gtk2_ui.h
@@ -105,7 +105,7 @@ class Gtk2UI : public views::LinuxUI {
                   std::vector<ui::TextEditCommandAuraLinux>* commands) override;
 
   // ui::Views::LinuxUI:
-  void UpdateDeviceScaleFactor(float device_scale_factor) override;
+  void UpdateDeviceScaleFactor() override;
   float GetDeviceScaleFactor() const override;
 
  private:
@@ -200,7 +200,7 @@ class Gtk2UI : public views::LinuxUI {
   // instance.
   NativeThemeGetter native_theme_overrider_;
 
-  float device_scale_factor_;
+  float device_scale_factor_ = 1.0f;
 
   DISALLOW_COPY_AND_ASSIGN(Gtk2UI);
 };