Support null language for fallbackFontForChar's IPC wrapper

content/browser/renderer_host/sandbox_ipc_linux.cc

Index: content/browser/renderer_host/sandbox_ipc_linux.cc
diff --git a/content/browser/renderer_host/sandbox_ipc_linux.cc b/content/browser/renderer_host/sandbox_ipc_linux.cc
index 74a1601c5782c8e12098e1228f6cecdb09d3dfd7..8deaef9be071625415367e0b6980cf7aca9d5a79 100644
--- a/content/browser/renderer_host/sandbox_ipc_linux.cc
+++ b/content/browser/renderer_host/sandbox_ipc_linux.cc
@@ -223,12 +223,20 @@ void SandboxIPCHandler::HandleGetFallbackFontForChar(
   if (!pickle.ReadInt(&iter, &c))
     return;
 
-  std::string preferred_locale;
-  if (!pickle.ReadString(&iter, &preferred_locale))
+  bool hasLocale;
+  if (!pickle.ReadBool(&iter, &hasLocale))
     return;
 
   blink::WebFallbackFont fallbackFont;
-  WebFontInfo::fallbackFontForChar(c, preferred_locale.c_str(), &fallbackFont);
+  if (hasLocale) {
+    std::string preferred_locale;
+    if (!pickle.ReadString(&iter, &preferred_locale))
+      return;
+    WebFontInfo::fallbackFontForChar(
+        c, preferred_locale.c_str(), &fallbackFont);
+  } else {
+    WebFontInfo::fallbackFontForChar(c, 0, &fallbackFont);
+  }
 
   int pathIndex = FindOrAddPath(SkString(fallbackFont.filename.data()));
   fallbackFont.fontconfigInterfaceId = pathIndex;