Consistently use snake_case for variable names.

This patch does not change behaviour, but makes the code style more
consistent.

Change-Id: I6ab07de8e98eb33800ccad8b0558cfaa22701ccb
diff --git a/src/utils-vixl.h b/src/utils-vixl.h
index 64608c1..e57cbee 100644
--- a/src/utils-vixl.h
+++ b/src/utils-vixl.h
@@ -508,11 +508,11 @@
 
 
 template <typename T>
-inline T SignExtend(T val, int bitSize) {
-  VIXL_ASSERT(bitSize > 0);
-  T mask = (T(2) << (bitSize - 1)) - T(1);
+inline T SignExtend(T val, int size_in_bits) {
+  VIXL_ASSERT(size_in_bits > 0);
+  T mask = (T(2) << (size_in_bits - 1)) - T(1);
   val &= mask;
-  T sign_bits = -((val >> (bitSize - 1)) << bitSize);
+  T sign_bits = -((val >> (size_in_bits - 1)) << size_in_bits);
   val |= sign_bits;
   return val;
 }