Move resource related IPCs to their own file in content.

ipc/ipc_message_macros.h

 // Copyright (c) 2011 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.
 
 // Defining IPC Messages
 //
 // Your IPC messages will be defined by macros inside of an XXX_messages.h
 // header file.  Most of the time, the system can automatically generate all
 // of messaging mechanism from these definitions, but sometimes some manual
 // coding is required.  In these cases, you will also have an XXX_messages.cc
@@ skipping 112 matching lines @@
 //
 // New structs are defined with IPC_STRUCT_BEGIN(), IPC_STRUCT_MEMBER(),
 // IPC_STRUCT_END() family of macros.  These cause the XXX_messages.h
 // to proclaim equivalent struct declarations for use by callers, as well
 // as later registering the type with the message generation.  Note that
 // IPC_STRUCT_MEMBER() is only permitted inside matching calls to
 // IPC_STRUCT_BEGIN() / IPC_STRUCT_END().
 //
 // Externally-defined structs are registered with IPC_STRUCT_TRAITS_BEGIN(),
 // IPC_STRUCT_TRAITS_MEMBER(), and IPC_STRUCT_TRAITS_END() macros. These
-// cause registration of the types with message generation only.  Note that
-// IPC_STRUCT_TRAITS_MEMBER() is only permitted inside matching calls
-// to IPC_STRUCT_TRAITS_BEGIN() / IPC_STRUCT_TRAITS_END().
+// cause registration of the types with message generation only.
+// There's also IPC_STRUCT_TRAITS_PARENT, which is used to register a parent
+// class (whose own traits are already defined). Note that
+// IPC_STRUCT_TRAITS_MEMBER() and IPC_STRUCT_TRAITS_PARENT are only permitted
+// inside matching calls to IPC_STRUCT_TRAITS_BEGIN() / IPC_STRUCT_TRAITS_END().
 //
 // Enum types are registered with a single IPC_ENUM_TRAITS() macro.  There
 // is no need to enumerate each value to the IPC mechanism.
 //
 // Once the types have been declared / registered, message definitions follow.
 // "Sync" messages are just synchronous calls, the Send() call doesn't return
 // until a reply comes back.  Input parameters are first (const TYPE&), and
 // To declare a sync message, use the IPC_SYNC_ macros.  The numbers at the
 // end show how many input/output parameters there are (i.e. 1_2 is 1 in, 2
 // out). The caller does a Send([route id, ], in1, &out1, &out2).
@@ skipping 608 matching lines @@
 #define IPC_MESSAGE_CLASS(message) \
   message.type() >> 16
 
 #endif  // IPC_IPC_MESSAGE_MACROS_H_
 
 // Clean up IPC_MESSAGE_START in this unguarded section so that the
 // XXX_messages.h files need not do so themselves.  This makes the
 // XXX_messages.h files easier to write.
 #undef IPC_MESSAGE_START