Use the WebKit default fonts when specifying generic font families.

webkit/plugins/ppapi/plugin_delegate.h

Index: webkit/plugins/ppapi/plugin_delegate.h
===================================================================
--- webkit/plugins/ppapi/plugin_delegate.h	(revision 86722)
+++ webkit/plugins/ppapi/plugin_delegate.h	(working copy)
@@ -48,6 +48,10 @@
 class CommandBuffer;
 }
 
+namespace ppapi {
+struct Preferences;
+}
+
 namespace skia {
 class PlatformCanvas;
 }
@@ -398,6 +402,9 @@
   // Create an anonymous shared memory segment of size |size| bytes, and return
   // a pointer to it, or NULL on error.  Caller owns the returned pointer.
   virtual base::SharedMemory* CreateAnonymousSharedMemory(uint32_t size) = 0;
+
+  // Returns the current preferences.
+  virtual ::ppapi::Preferences GetPreferences() = 0;
 };
 
 }  // namespace ppapi