Disk cache: A few minor fixes to make coverity happy.

net/disk_cache/file_win.cc

Index: net/disk_cache/file_win.cc
===================================================================
--- net/disk_cache/file_win.cc	(revision 12016)
+++ net/disk_cache/file_win.cc	(working copy)
@@ -62,7 +62,9 @@
 MyOverlapped::~MyOverlapped() {
   if (delete_buffer_) {
     DCHECK(!callback_);
-    delete buffer_;
+    // This whole thing could be updated to use IOBuffer, but PostWrite is not
+    // used at the moment. TODO(rvargas): remove or update this code.
+    delete[] reinterpret_cast<const char*>(buffer_);
   }
 }