Remove an MSVC-required macro.

BUG=none

Change-Id: I118976f80f3c605f7b2c5cb05e8b60278fded19d
Reviewed-on: https://chromium-review.googlesource.com/c/1272495Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599047}

base/component_export.h

@@ -72,16 +72,7 @@
 // |COMPONENT_MACRO_CONDITIONAL_COMMA_()| above to implement conditional macro
 // expansion.
 #define COMPONENT_MACRO_SELECT_THIRD_ARGUMENT_(...) \
-  COMPONENT_MACRO_EXPAND_(                          \
-      COMPONENT_MACRO_SELECT_THIRD_ARGUMENT_IMPL_(__VA_ARGS__))
+  COMPONENT_MACRO_SELECT_THIRD_ARGUMENT_IMPL_(__VA_ARGS__)
 #define COMPONENT_MACRO_SELECT_THIRD_ARGUMENT_IMPL_(a, b, c, ...) c
 
-// Helper to work around MSVC quirkiness wherein a macro expansion like |,|
-// within a parameter list will be treated as a single macro argument. This is
-// needed to ensure that |COMPONENT_MACRO_CONDITIONAL_COMMA_()| above can expand
-// to multiple separate positional arguments in the affirmative case, thus
-// elliciting the desired conditional behavior with
-// |COMPONENT_MACRO_SELECT_THIRD_ARGUMENT_()|.
-#define COMPONENT_MACRO_EXPAND_(x) x
-
 #endif  // BASE_COMPONENT_EXPORT_H_

base/macros.h

@@ -89,10 +89,6 @@ namespace base {
 #define CR_DEFINE_STATIC_LOCAL(type, name, arguments) \
   static type& name = *new type arguments
 
-// Workaround for MSVC, which expands __VA_ARGS__ as one macro argument. To
-// work around this bug, wrap the entire expression in this macro...
-#define CR_EXPAND_ARG(arg) arg
-
 }  // base
 
 #endif  // BASE_MACROS_H_

base/metrics/histogram_macros.h

@@ -77,10 +77,10 @@
 // enum to an arithmetic type and adding one. Instead, prefer the two argument
 // version of the macro which automatically deduces the boundary from kMaxValue.
 #define UMA_HISTOGRAM_ENUMERATION(name, ...)                            \
-  CR_EXPAND_ARG(INTERNAL_UMA_HISTOGRAM_ENUMERATION_GET_MACRO(           \
+  INTERNAL_UMA_HISTOGRAM_ENUMERATION_GET_MACRO(                         \
       __VA_ARGS__, INTERNAL_UMA_HISTOGRAM_ENUMERATION_SPECIFY_BOUNDARY, \
-      INTERNAL_UMA_HISTOGRAM_ENUMERATION_DEDUCE_BOUNDARY)(              \
-      name, __VA_ARGS__, base::HistogramBase::kUmaTargetedHistogramFlag))
+      INTERNAL_UMA_HISTOGRAM_ENUMERATION_DEDUCE_BOUNDARY)               \
+  (name, __VA_ARGS__, base::HistogramBase::kUmaTargetedHistogramFlag)
 
 // As above but "scaled" count to avoid overflows caused by increments of
 // large amounts. See UMA_HISTOGRAM_SCALED_EXACT_LINEAR for more information.

base/metrics/histogram_macros_local.h

@@ -19,10 +19,10 @@
 // For usage details, see the equivalents in histogram_macros.h.
 
 #define LOCAL_HISTOGRAM_ENUMERATION(name, ...)                          \
-  CR_EXPAND_ARG(INTERNAL_UMA_HISTOGRAM_ENUMERATION_GET_MACRO(           \
+  INTERNAL_UMA_HISTOGRAM_ENUMERATION_GET_MACRO(                         \
       __VA_ARGS__, INTERNAL_UMA_HISTOGRAM_ENUMERATION_SPECIFY_BOUNDARY, \
-      INTERNAL_UMA_HISTOGRAM_ENUMERATION_DEDUCE_BOUNDARY)(              \
-      name, __VA_ARGS__, base::HistogramBase::kNoFlags))
+      INTERNAL_UMA_HISTOGRAM_ENUMERATION_DEDUCE_BOUNDARY)               \
+  (name, __VA_ARGS__, base::HistogramBase::kNoFlags)
 
 #define LOCAL_HISTOGRAM_BOOLEAN(name, sample)                                  \
     STATIC_HISTOGRAM_POINTER_BLOCK(name, AddBoolean(sample),                   \