Changes to ALLOW_UNUSED to match upcoming changes to the Chromium trunk:

src/base/compiler-specific.h

Index: src/base/compiler-specific.h
diff --git a/src/base/compiler-specific.h b/src/base/compiler-specific.h
index 475a32c2c1032b0e31f275e25849b6aa9f4d5f42..fccac9f382745da7672c39e5a81b6546cc02aef9 100644
--- a/src/base/compiler-specific.h
+++ b/src/base/compiler-specific.h
@@ -7,15 +7,13 @@
 
 #include "include/v8config.h"
 
-// Annotate a variable indicating it's ok if the variable is not used.
-// (Typically used to silence a compiler warning when the assignment
-// is important for some other reason.)
+// Annotate a typedef or function indicating it's ok if it's not used.
 // Use like:
-//   int x ALLOW_UNUSED = ...;
+//   typedef Foo Bar ALLOW_UNUSED_TYPE;
 #if V8_HAS_ATTRIBUTE_UNUSED
-#define ALLOW_UNUSED __attribute__((unused))
+#define ALLOW_UNUSED_TYPE __attribute__((unused))
 #else
-#define ALLOW_UNUSED
+#define ALLOW_UNUSED_TYPE
 #endif