Add GL strings to CastSysInfo interface and use to configure GPU

chromecast/base/cast_sys_info_dummy.h

Index: chromecast/base/cast_sys_info_dummy.h
diff --git a/chromecast/base/cast_sys_info_dummy.h b/chromecast/base/cast_sys_info_dummy.h
index 0b804a2d50a22a309ab685a624c050113eb7f254..2c8a4a8d4e858adea4536a3b6d8dee867de9c6c1 100644
--- a/chromecast/base/cast_sys_info_dummy.h
+++ b/chromecast/base/cast_sys_info_dummy.h
@@ -29,6 +29,8 @@ class CastSysInfoDummy : public CastSysInfo {
   std::string GetFactoryLocale(std::string* second_locale) override;
   std::string GetWifiInterface() override;
   std::string GetApInterface() override;
+  std::string GetGpuVendor() override;
+  std::string GetGpuModel() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CastSysInfoDummy);