Fix Pango font rendering with HiDPi displays on Linux.

ui/gfx/platform_font_linux.cc

Index: ui/gfx/platform_font_linux.cc
diff --git a/ui/gfx/platform_font_linux.cc b/ui/gfx/platform_font_linux.cc
index 2f1bbf14b8e1804e42f15374f7049546f58de267..2a1cb41dd789dec60d4b6c2844ae73ee2b6190a0 100644
--- a/ui/gfx/platform_font_linux.cc
+++ b/ui/gfx/platform_font_linux.cc
@@ -91,7 +91,7 @@ PlatformFontLinux::PlatformFontLinux() {
 #else
     // On Linux, LinuxFontDelegate is used to query the native toolkit (e.g.
     // GTK+) for the default UI font.
-    const LinuxFontDelegate* delegate = LinuxFontDelegate::instance();
+    LinuxFontDelegate* delegate = LinuxFontDelegate::instance();
     if (delegate) {
       delegate->GetDefaultFontDescription(
           &family, &size_pixels, &style, &params);