IPC::Message -> base::Pickle

base/pickle.h

Index: base/pickle.h
diff --git a/base/pickle.h b/base/pickle.h
index 02bc432ad0bd27564e289f9d8fae0b9ca9408241..2487aebc3e6bbb74551204b9e56ee58c89f88e00 100644
--- a/base/pickle.h
+++ b/base/pickle.h
@@ -14,6 +14,7 @@
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
+#include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
 
@@ -123,6 +124,19 @@ class BASE_EXPORT PickleIterator {
 //
 class BASE_EXPORT Pickle {
  public:
+  // A base attachment type for a Pickle subclass to implement if it supports
+  // reading and writing attachments.
+  class BASE_EXPORT Attachment : public RefCountedThreadSafe<Attachment> {
+   public:
+    Attachment();
+
+   protected:
+    friend class RefCountedThreadSafe<Attachment>;
+    virtual ~Attachment();
+
+    DISALLOW_COPY_AND_ASSIGN(Attachment);
+  };
+
   // Initialize a Pickle object using the default header size.
   Pickle();
 
@@ -206,6 +220,23 @@ class BASE_EXPORT Pickle {
   // known size. See also WriteData.
   bool WriteBytes(const void* data, int length);
 
+  // WriteAttachment appends |attachment| to the pickle. It returns
+  // false iff the set is full.
+  //
+  // NOTE: It is NOT OK to call this or ReadAttachment() on a simple

[Tom Sepez, 2016/02/02 19:25:55]

It feels wrong to design a virtual API that requires knowing the concrete type
of the underlying class to avoid a NOTREACHED().  I'd be happier if we returned
false in that case and that false means the set is full or the pickle doesn't
support attachments.

+  // base::Pickle. These must be implemented and called only on subclasses that
+  // support attachments.
+  virtual bool WriteAttachment(scoped_refptr<Attachment> attachment);
+
+  // ReadAttachment parses an attachment given the parsing state |iter| and
+  // writes it to |*attachment|. It returns true on success.
+  //
+  // NOTE: It is NOT OK to call this or WriteAttachment() on a simple
+  // base::Pickle. These must be implemented and called only subclasses that
+  // support attachments.
+  virtual bool ReadAttachment(base::PickleIterator* iter,
+                              scoped_refptr<Attachment>* attachment) const;
+
   // Reserves space for upcoming writes when multiple writes will be made and
   // their sizes are computed in advance. It can be significantly faster to call
   // Reserve() before calling WriteFoo() multiple times.