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}

2 files changed, 7 insertions, 4 deletions

diff --git a/device/bluetooth/bluetooth_uuid.cc b/device/bluetooth/bluetooth_uuid.cc
index 89c1ac6..7a275e5 100644
--- a/device/bluetooth/bluetooth_uuid.cc
+++ b/device/bluetooth/bluetooth_uuid.cc
@@ -96,12 +96,12 @@ void PrintTo(const BluetoothUUID& uuid, std::ostream* out) {
 
 }  // namespace device
 
-void IPC::ParamTraits<device::BluetoothUUID>::Write(Message* m,
+void IPC::ParamTraits<device::BluetoothUUID>::Write(base::Pickle* m,
                                                     const param_type& p) {
   m->WriteString(p.canonical_value());
 }
 
-bool IPC::ParamTraits<device::BluetoothUUID>::Read(const Message* m,
+bool IPC::ParamTraits<device::BluetoothUUID>::Read(const base::Pickle* m,
                                                    base::PickleIterator* iter,
                                                    param_type* r) {
   std::string value;
diff --git a/device/bluetooth/bluetooth_uuid.h b/device/bluetooth/bluetooth_uuid.h
index 5d7cdd2..f36e8b5 100644
--- a/device/bluetooth/bluetooth_uuid.h
+++ b/device/bluetooth/bluetooth_uuid.h
@@ -11,6 +11,7 @@
 #include "ipc/ipc_param_traits.h"
 
 namespace base {
+class Pickle;
 class PickleIterator;
 }  // namespace base
 
@@ -110,8 +111,10 @@ class Message;
 template <>
 struct DEVICE_BLUETOOTH_EXPORT ParamTraits<device::BluetoothUUID> {
   typedef device::BluetoothUUID 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);
 };