Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/build/scripts/templates/InternalSettingsGenerated.idl.tmpl

 {% from "macros.tmpl" import license %}
 {{ license() }}
 
 [
-    WillBeGarbageCollected,
+    GarbageCollected,
 ] interface InternalSettingsGenerated {
     {% for setting in settings if setting.type|to_idl_type %}
     void set{{setting.name|upper_first}}({{setting.type|to_idl_type}} {{setting.name}});
     {% endfor %}
 };