Implement out-of-process proxy for PPB_Buffer_Dev.

ppapi/cpp/dev/buffer_dev.h

Index: ppapi/cpp/dev/buffer_dev.h
diff --git a/ppapi/cpp/dev/buffer_dev.h b/ppapi/cpp/dev/buffer_dev.h
index 83c265c2bfa29acf639593f3dd1bab4d12b9157f..34c0a003c55d2210b4f482d1c9ef2e11dd94373d 100644
--- a/ppapi/cpp/dev/buffer_dev.h
+++ b/ppapi/cpp/dev/buffer_dev.h
@@ -15,13 +15,15 @@ class Buffer_Dev : public Resource {
  public:
   // Creates an is_null() Buffer object.
   Buffer_Dev();
-
   Buffer_Dev(const Buffer_Dev& other);
 
-  // Allocates a new Buffer in the browser with the given size. The
-  // resulting object will be is_null() if the allocation failed.
+  // Creates & Maps a new Buffer in the browser with the given size. The
+  // resulting object will be is_null() if either Create() or Map() fails.
   Buffer_Dev(Instance* instance, uint32_t size);
 
+  // Unmap the underlying shared memory.
+  virtual ~Buffer_Dev();
+
   uint32_t size() const { return size_; }
   void* data() const { return data_; }
 
@@ -33,4 +35,3 @@ class Buffer_Dev : public Resource {
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_BUFFER_DEV_H_
-