Allow the default generic font family settings to find the first available font

third_party/WebKit/Source/platform/fonts/FontCache.cpp

Index: third_party/WebKit/Source/platform/fonts/FontCache.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/FontCache.cpp b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
index 2844a92e37aa811a9dd023d1d65441be65a5e5da..1ac542a2c04fdca50461f0c8a3c724346acec6b4 100644
--- a/third_party/WebKit/Source/platform/fonts/FontCache.cpp
+++ b/third_party/WebKit/Source/platform/fonts/FontCache.cpp
@@ -48,6 +48,7 @@
 #include "platform/tracing/web_memory_allocator_dump.h"
 #include "platform/tracing/web_process_memory_dump.h"
 #include "public/platform/Platform.h"
+#include "ui/gfx/font_list.h"
 #include "wtf/HashMap.h"
 #include "wtf/ListHashSet.h"
 #include "wtf/PtrUtil.h"
@@ -303,6 +304,15 @@ bool FontCache::isPlatformFontAvailable(const FontDescription& fontDescription,
       checkingAlternateName);
 }
 
+String FontCache::firstAvailableOrFirst(const String& families) {
+  // The conversions involve at least two string copies, and more if non-ASCII.
+  // For now we prefer shared code over the cost because a) inputs are
+  // only from grd/xtb and all ASCII, and b) at most only a few times per
+  // setting change/script.
+  return String::fromUTF8(
+      gfx::FontList::FirstAvailableOrFirst(families.utf8().data()).c_str());
+}
+
 SimpleFontData* FontCache::getNonRetainedLastResortFallbackFont(
     const FontDescription& fontDescription) {
   return getLastResortFallbackFont(fontDescription, DoNotRetain).leakRef();