IPC::Message -> base::Pickle

This changes consumers of IPC::Message to generally refer
refer to base::Pickle instead when performing serialization
and deserialization operations. The few specific instances
where the IPC::Message interface (Read/WriteAttachent) is
needed can safely be static_cast'd, as IPC::Message is the
only public subclass of base::Pickle.

The purpose of this change is to facilitate the transition
to Mojo IPC, as we've trained the Mojo bindings layer to
use existing ParamTraits<T> parameterized over base::Pickle.

To support this base::Pickle has had some stub interfaces
added for WriteAttachment and ReadAttachment, along with a
Pickle::Attachment.

A follow-up patch will add sizing traits to the standard
IPC_STRUCT macros, enabling the majority of Chrome IPC
structs to be carried over Mojo message pipes as-is.

BUG=577685
R=jam@chromium.org

Review URL: https://codereview.chromium.org/1659003003

Cr-Commit-Position: refs/heads/master@{#373323}

1 files changed, 20 insertions, 10 deletions

diff --git a/remoting/host/chromoting_param_traits.h b/remoting/host/chromoting_param_traits.h
index 9da88f8..b13bc82 100644
--- a/remoting/host/chromoting_param_traits.h
+++ b/remoting/host/chromoting_param_traits.h
@@ -17,40 +17,50 @@ namespace IPC {
 template <>
 struct ParamTraits<webrtc::DesktopVector> {
   typedef webrtc::DesktopVector param_type;
-  static void Write(Message* m, const param_type& p);
-  static bool Read(const Message* m, base::PickleIterator* iter, param_type* r);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
 struct ParamTraits<webrtc::DesktopSize> {
   typedef webrtc::DesktopSize param_type;
-  static void Write(Message* m, const param_type& p);
-  static bool Read(const Message* m, base::PickleIterator* iter, param_type* r);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
 struct ParamTraits<webrtc::DesktopRect> {
   typedef webrtc::DesktopRect param_type;
-  static void Write(Message* m, const param_type& p);
-  static bool Read(const Message* m, base::PickleIterator* iter, param_type* r);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
 struct ParamTraits<webrtc::MouseCursor> {
   typedef webrtc::MouseCursor param_type;
-  static void Write(Message* m, const param_type& p);
-  static bool Read(const Message* m, base::PickleIterator* iter, param_type* r);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
 struct ParamTraits<remoting::ScreenResolution> {
   typedef remoting::ScreenResolution param_type;
-  static void Write(Message* m, const param_type& p);
-  static bool Read(const Message* m, base::PickleIterator* iter, param_type* r);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* r);
   static void Log(const param_type& p, std::string* l);
 };