Tweak SVNVersion be happier (matches windows)....

base/file_version_info_mac.mm

Index: base/file_version_info_mac.mm
===================================================================
--- base/file_version_info_mac.mm	(revision 17147)
+++ base/file_version_info_mac.mm	(working copy)
@@ -103,11 +103,15 @@
 }
 
 std::wstring FileVersionInfo::last_change() {
-  return L"";
+  return GetStringValue(L"SVNRevision");
 }
 
 bool FileVersionInfo::is_official_build() {
+#if defined (GOOGLE_CHROME_BUILD)
+  return true;
+#else
   return false;
+#endif
 }
 
 bool FileVersionInfo::GetValue(const wchar_t* name, std::wstring* value_str) {