Set the font family for the "system-ui" generic font family on Linux

third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp

Index: third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp b/third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp
index 7fe3bd901ce58f8dc28c6de1f79b3cde85be2744..66a3909118e98686536ab305c32ca2f920b737b6 100644
--- a/third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp
+++ b/third_party/WebKit/Source/platform/fonts/android/FontCacheAndroid.cpp
@@ -39,6 +39,19 @@
 
 namespace blink {
 
+// static
+const AtomicString& FontCache::systemFontFamily()
+{
+    DEFINE_STATIC_LOCAL(AtomicString, systemFontFamilyName, ());
+    return systemFontFamilyName;
+}
+
+// static
+void FontCache::setSystemFontFamily(const char* familyName)
+{
+    NOTREACHED();
+}
+
 PassRefPtr<SimpleFontData> FontCache::fallbackFontForCharacter(const FontDescription& fontDescription, UChar32 c, const SimpleFontData*, FontFallbackPriority fallbackPriority)
 {
     sk_sp<SkFontMgr> fm(SkFontMgr::RefDefault());