Fix cpplint's whitespace complaints.

Change-Id: I11fd2db2badf7bd98e7866ca2155d8ef1e112408
diff --git a/src/os.h b/src/os.h
index 3d7c0fa..653f14d 100644
--- a/src/os.h
+++ b/src/os.h
@@ -27,7 +27,7 @@
  public:
 
   // Open a file. The returned file must be deleted by the caller.
-  static File* OpenFile(const char* name, bool writable, bool create=true);
+  static File* OpenFile(const char* name, bool writable, bool create = true);
 
   // Create a file from an already open file descriptor
   static File* FileFromFd(const char* name, int fd);