Mojo: Move platform handle/channel stuff in system to embedder namespace.

mojo/system/scoped_platform_handle.h

 // Copyright 2014 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 MOJO_SYSTEM_SCOPED_PLATFORM_HANDLE_H_
 #define MOJO_SYSTEM_SCOPED_PLATFORM_HANDLE_H_
 
 #include "base/compiler_specific.h"
 #include "base/move.h"
 #include "mojo/system/platform_handle.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
-namespace system {
+namespace embedder {
 
 class MOJO_SYSTEM_IMPL_EXPORT ScopedPlatformHandle {
   MOVE_ONLY_TYPE_FOR_CPP_03(ScopedPlatformHandle, RValue);
 
  public:
   ScopedPlatformHandle() {}
   explicit ScopedPlatformHandle(PlatformHandle handle) : handle_(handle) {}
   ~ScopedPlatformHandle() { handle_.CloseIfNecessary(); }
 
   // Move-only constructor and operator=.
@@ skipping 23 matching lines @@
   }
 
   bool is_valid() const {
     return handle_.is_valid();
   }
 
  private:
   PlatformHandle handle_;
 };
 
-}  // namespace system
+}  // namespace embedder
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_SCOPED_PLATFORM_HANDLE_H_