Unified the structure of VirtualMemory implementations across platforms a bit.

src/platform-openbsd.cc

Index: src/platform-openbsd.cc
diff --git a/src/platform-openbsd.cc b/src/platform-openbsd.cc
index aca03be3e5ac5197584f0614b8c089ae2a8e4a9b..4c29023c0a5b01c68b10981e53af21978b64970e 100644
--- a/src/platform-openbsd.cc
+++ b/src/platform-openbsd.cc
@@ -386,12 +386,12 @@ int OS::StackWalk(Vector<OS::StackFrame> frames) {
 static const int kMmapFd = -1;
 static const int kMmapFdOffset = 0;
 
+
 VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
 
-VirtualMemory::VirtualMemory(size_t size) {
-  address_ = ReserveRegion(size);
-  size_ = size;
-}
+
+VirtualMemory::VirtualMemory(size_t size)
+    : address_(ReserveRegion(size)), size_(size) { }
 
 
 VirtualMemory::VirtualMemory(size_t size, size_t alignment)