Replace WTF::Optional the base::Optional implementation.

third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.h

Index: third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.h
diff --git a/third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.h b/third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.h
index 378be34055786e63f489df812cae327940ad8569..8815e8ed9f2a2f83f380e4811334ef6eb93fe785 100644
--- a/third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.h
+++ b/third_party/WebKit/Source/platform/graphics/gpu/WebGLImageConversion.h
@@ -128,6 +128,8 @@ public:
 
     class PLATFORM_EXPORT ImageExtractor final {
         STACK_ALLOCATED();
+        WTF_MAKE_NONCOPYABLE(ImageExtractor);

[esprehn, 2016/04/20 00:28:03]

why this patch?

[danakj, 2016/04/20 00:37:21]

Windows debug generates a copy constructor for ImageExtractor even though it is
not used. Optional's copy constructor will copy ImagePixelLocker, who's copy
constructor is deleted, causing a compile failure.

You couldn't use the copy constructor anyways, for the same reasons, but this
prevents Windows debug from trying to generate it.

+
     public:
         ImageExtractor(Image*, ImageHtmlDomSource, bool premultiplyAlpha, bool ignoreGammaAndColorProfile);