Allow property setter function to take any arg type.

Instead of forcing ArgType<T>, just generically match a signature type.
This allows classes to choose to implement e.g. by reference or value,
at the cost of possibly-more-cryptic template errors when people don't
implement a setter.

We could probably give better errors than this with some helper structs
to restrict to e.g. single-arg member functions whose arg is convertible
from ArgType, but this seems good enough for now.

Bug: none
Change-Id: I079fd9dd5cd3cb51297855d2ccabde65148c0b6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363562
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Wei Li <weili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801146}

ui/views/metadata/metadata_macros_internal.h

@@ -51,7 +51,8 @@
 #define METADATA_PROPERTY_TYPE_INTERNAL(class_name, property_type,          \
                                         property_name)                      \
   views::metadata::ClassPropertyMetaData<                                   \
-      class_name, property_type, &class_name::Set##property_name,  \
+      class_name, property_type, decltype(&class_name::Set##property_name), \
+      &class_name::Set##property_name,                                      \
       decltype(std::declval<class_name>().Get##property_name()),            \
       &class_name::Get##property_name>
 

ui/views/metadata/property_metadata.h

@@ -49,7 +49,8 @@ class ClassPropertyReadOnlyMetaData : public MemberMetaDataBase {
 // (so it will trigger things like property changed notifications).
 template <typename TClass,
           typename TValue,
-          void (TClass::*Set)(ArgType<TValue>),
+          typename TSig,
+          TSig Set,
           typename TRet,
           TRet (TClass::*Get)() const>
 class ClassPropertyMetaData