Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/core/frame/FrameOwner.h

Index: third_party/WebKit/Source/core/frame/FrameOwner.h
diff --git a/third_party/WebKit/Source/core/frame/FrameOwner.h b/third_party/WebKit/Source/core/frame/FrameOwner.h
index 9352a7a71f51a20fc31c903e5a0537c2984c07b6..7df404ccdf9e1bf1fbfbe02de3c62cd06ccc2377 100644
--- a/third_party/WebKit/Source/core/frame/FrameOwner.h
+++ b/third_party/WebKit/Source/core/frame/FrameOwner.h
@@ -15,7 +15,7 @@ namespace blink {
 // Oilpan: all FrameOwner instances are GCed objects. FrameOwner additionally
 // derives from GarbageCollectedMixin so that Member<FrameOwner> references can
 // be kept (e.g., Frame::m_owner.)
-class CORE_EXPORT FrameOwner : public WillBeGarbageCollectedMixin {
+class CORE_EXPORT FrameOwner : public GarbageCollectedMixin {
 public:
     virtual ~FrameOwner() { }
     DEFINE_INLINE_VIRTUAL_TRACE() { }