Unified the structure of VirtualMemory implementations across platforms a bit.

src/platform-macos.cc

Index: src/platform-macos.cc
diff --git a/src/platform-macos.cc b/src/platform-macos.cc
index 898c93f39a346003ae53724cc290df362c12d5ed..8327acfb5f13170d7098233d4ed0aebc596ed157 100644
--- a/src/platform-macos.cc
+++ b/src/platform-macos.cc
@@ -408,12 +408,33 @@ VirtualMemory::~VirtualMemory() {
 }
 
 
+bool VirtualMemory::IsReserved() {
+  return address_ != NULL;
+}
+
+
 void VirtualMemory::Reset() {
   address_ = NULL;
   size_ = 0;
 }
 
 
+bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
+  return CommitRegion(address, size, is_executable);
+}
+
+
+bool VirtualMemory::Uncommit(void* address, size_t size) {
+  return UncommitRegion(address, size);
+}
+
+
+bool VirtualMemory::Guard(void* address) {
+  OS::Guard(address, OS::CommitPageSize());
+  return true;
+}
+
+
 void* VirtualMemory::ReserveRegion(size_t size) {
   void* result = mmap(OS::GetRandomMmapAddr(),
                       size,
@@ -428,22 +449,6 @@ void* VirtualMemory::ReserveRegion(size_t size) {
 }
 
 
-bool VirtualMemory::IsReserved() {
-  return address_ != NULL;
-}
-
-
-bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
-  return CommitRegion(address, size, is_executable);
-}
-
-
-bool VirtualMemory::Guard(void* address) {
-  OS::Guard(address, OS::CommitPageSize());
-  return true;
-}
-
-
 bool VirtualMemory::CommitRegion(void* address,
                                  size_t size,
                                  bool is_executable) {
@@ -462,11 +467,6 @@ bool VirtualMemory::CommitRegion(void* address,
 }
 
 
-bool VirtualMemory::Uncommit(void* address, size_t size) {
-  return UncommitRegion(address, size);
-}
-
-
 bool VirtualMemory::UncommitRegion(void* address, size_t size) {
   return mmap(address,
               size,