Add flag to disable mmap in all sql connection

sql/connection.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SQL_CONNECTION_H_
 #define SQL_CONNECTION_H_
 
 #include <stddef.h>
 #include <stdint.h>
 #include <map>
@@ skipping 131 matching lines @@
   //
   // This must be called before Open() to have an effect.
   void set_exclusive_locking() { exclusive_locking_ = true; }
 
   // Call to cause Open() to restrict access permissions of the
   // database file to only the owner.
   // TODO(shess): Currently only supported on OS_POSIX, is a noop on
   // other platforms.
   void set_restrict_to_user() { restrict_to_user_ = true; }
 
-  // Call to opt out of memory-mapped file I/O.
+  // Call to opt out of memory-mapped file I/O on per connection basis.
   void set_mmap_disabled() { mmap_disabled_ = true; }
 
+  // Call to opt out of memory-mapped file I/O on all connections.
+  static void set_mmap_disabled_by_default();
+
   // Set an error-handling callback.  On errors, the error number (and
   // statement, if available) will be passed to the callback.
   //
   // If no callback is set, the default action is to crash in debug
   // mode or return failure in release mode.
   typedef base::Callback<void(int, Statement*)> ErrorCallback;
   void set_error_callback(const ErrorCallback& callback) {
     error_callback_ = callback;
   }
   bool has_error_callback() const {
@@ skipping 628 matching lines @@
 
   // Stores the dump provider object when db is open.
   scoped_ptr<ConnectionMemoryDumpProvider> memory_dump_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(Connection);
 };
 
 }  // namespace sql
 
 #endif  // SQL_CONNECTION_H_