Nuke WebPassOwnPtr<T> and replace it with std::unique_ptr<T>.

third_party/WebKit/public/platform/WebCallbacks.h

Index: third_party/WebKit/public/platform/WebCallbacks.h
diff --git a/third_party/WebKit/public/platform/WebCallbacks.h b/third_party/WebKit/public/platform/WebCallbacks.h
index 51f83ae16b3bddfd574116616b708efd6677f671..9cf230d0aa133535a8200ba202ddfbc9570fed77 100644
--- a/third_party/WebKit/public/platform/WebCallbacks.h
+++ b/third_party/WebKit/public/platform/WebCallbacks.h
@@ -31,14 +31,12 @@
 #ifndef WebCallbacks_h
 #define WebCallbacks_h
 
-#include "public/platform/WebPassOwnPtr.h"
-
 namespace blink {
 
 // A WebCallbacks<S, T> represents a callback object. Typically it is created
 // in Blink and passed to Chromium, and onSuccess or onError will be called
 // from Chromium.
-// When transferring ownership, use |WebPrivatePassOwnPtr<X>| as a type
+// When transferring ownership, use |std::unique_ptr<X>| as a type
 // parameter. Otherwise, |const X&| or |X| for a type parameter. It is
 // generally not preferred to use |X*| because the object ownership is not well
 // specified.