Add variations filtering for is_low_end_device.

components/variations/study_filtering.h

Index: components/variations/study_filtering.h
diff --git a/components/variations/study_filtering.h b/components/variations/study_filtering.h
index a5667cdb6cb5dd0440155c3b3226e9d74d7b47bd..87b4fae996f1384216fcab4b14969656ac9ee2af 100644
--- a/components/variations/study_filtering.h
+++ b/components/variations/study_filtering.h
@@ -41,6 +41,10 @@ bool CheckStudyLocale(const Study::Filter& filter, const std::string& locale);
 // Checks whether a study is applicable for the given |platform| per |filter|.
 bool CheckStudyPlatform(const Study::Filter& filter, Study::Platform platform);
 
+// Checks whether a study is applicable given |is_low_end_device| per |filter|.
+bool CheckStudyLowEndDevice(const Study::Filter& filter,
+                            bool is_low_end_device);
+
 // Checks whether a study is applicable for the given date/time per |filter|.
 bool CheckStudyStartDate(const Study::Filter& filter,
                          const base::Time& date_time);