Access the value directly in Optional::value_or

value_or() called value() to get the value, but that resulted in
executing a redundant CHECK() statement. This is not guaranteed to be
optimised out. Also it is annoying when stepping through in a debugger.

Access the value directly rather than calling value().

Change-Id: I0037abf32e1fe0417ee8083ca8e4ae67c8446de7
Reviewed-on: https://chromium-review.googlesource.com/1110178Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569568}

base/optional.h

@@ -636,7 +636,7 @@ class OPTIONAL_DECLSPEC_EMPTY_BASES Optional
     static_assert(std::is_convertible<U, T>::value,
                   "U must be convertible to T");
     return storage_.is_populated_
-               ? value()
+               ? storage_.value_
                : static_cast<T>(std::forward<U>(default_value));
   }
 
@@ -648,7 +648,7 @@ class OPTIONAL_DECLSPEC_EMPTY_BASES Optional
     static_assert(std::is_convertible<U, T>::value,
                   "U must be convertible to T");
     return storage_.is_populated_
-               ? std::move(value())
+               ? std::move(storage_.value_)
                : static_cast<T>(std::forward<U>(default_value));
   }