Mojo: Add embedder::PlatformSupport and a simple implementation (and a bit of plumbing).

mojo/system/shared_buffer_dispatcher.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_SHARED_BUFFER_DISPATCHER_H_
 #define MOJO_SYSTEM_SHARED_BUFFER_DISPATCHER_H_
 
 #include "base/macros.h"
 #include "mojo/embedder/platform_shared_buffer.h"
 #include "mojo/system/memory.h"
 #include "mojo/system/simple_dispatcher.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
+
+namespace embedder {
+class PlatformSupport;
+}
+
 namespace system {
 
 // TODO(vtl): We derive from SimpleDispatcher, even though we don't currently
 // have anything that's waitable. I want to add a "transferrable" wait flag
 // (which would entail overriding |GetHandleSignalsStateImplNoLock()|, etc.).
 class MOJO_SYSTEM_IMPL_EXPORT SharedBufferDispatcher : public SimpleDispatcher {
  public:
   // The default options to use for |MojoCreateSharedBuffer()|. (Real uses
   // should obtain this via |ValidateCreateOptions()| with a null |in_options|;
   // this is exposed directly for testing convenience.)
   static const MojoCreateSharedBufferOptions kDefaultCreateOptions;
 
   // Validates and/or sets default options for |MojoCreateSharedBufferOptions|.
   // If non-null, |in_options| must point to a struct of at least
   // |in_options->struct_size| bytes. |out_options| must point to a (current)
   // |MojoCreateSharedBufferOptions| and will be entirely overwritten on success
   // (it may be partly overwritten on failure).
   static MojoResult ValidateCreateOptions(
       UserPointer<const MojoCreateSharedBufferOptions> in_options,
       MojoCreateSharedBufferOptions* out_options);
 
   // Static factory method: |validated_options| must be validated (obviously).
   // On failure, |*result| will be left as-is.
   static MojoResult Create(
+      embedder::PlatformSupport* platform_support,
       const MojoCreateSharedBufferOptions& validated_options,
       uint64_t num_bytes,
       scoped_refptr<SharedBufferDispatcher>* result);
 
   // |Dispatcher| public methods:
   virtual Type GetType() const OVERRIDE;
 
   // The "opposite" of |SerializeAndClose()|. (Typically this is called by
   // |Dispatcher::Deserialize()|.)
   static scoped_refptr<SharedBufferDispatcher> Deserialize(
@@ skipping 39 matching lines @@
 
   scoped_refptr<embedder::PlatformSharedBuffer> shared_buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(SharedBufferDispatcher);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_SHARED_BUFFER_DISPATCHER_H_