Revert of IPC: Add attachment brokering support to the message header. (patchset #20 id:420001 of https://codereview.chromium.org/1286253002/ )

Reason for revert:
Suspected of breaking XP Tests. See, for example https://build.chromium.org/p/chromium.win/builders/XP%20Tests%20%281%29/builds/39586 .

Original issue's description:
> IPC: Add attachment brokering support to the message header.
>
> Message dispatch happens before message translation, and message dispatch
> requires that all brokered attachments have been received. This means that
> attachment brokering needs to function without message translation. This is
> accomplished by modifying the message header to include a new field
> num_brokered_attachments, and writing the attachment ids into the IPC Channel
> immediately following the pickled message itself.
>
> AttachmentBrokerPrivilegedWinUnittest was expanded to test ChannelReader in the
> receiving process. It is now a fully functional end-to-end test of attachment
> brokering.
>
> BUG=493414
>
> Committed: https://crrev.com/e8e4f4fa67ee9db6c2910020ef49318e5df68481
> Cr-Commit-Position: refs/heads/master@{#344389}

TBR=tsepez@chromium.org,thakis@chromium.org,erikchen@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=493414

Review URL: https://codereview.chromium.org/1286883003

Cr-Commit-Position: refs/heads/master@{#344461}

1 files changed, 6 insertions, 26 deletions

diff --git a/ipc/ipc_channel.h b/ipc/ipc_channel.h
index 9021ab4..c74d084 100644
--- a/ipc/ipc_channel.h
+++ b/ipc/ipc_channel.h
@@ -52,7 +52,7 @@ class IPC_EXPORT Channel : public Endpoint {
     MODE_CLIENT_FLAG = 0x2,
     MODE_NAMED_FLAG = 0x4,
 #if defined(OS_POSIX)
-    MODE_OPEN_ACCESS_FLAG = 0x8,  // Don't restrict access based on client UID.
+    MODE_OPEN_ACCESS_FLAG = 0x8, // Don't restrict access based on client UID.
 #endif
   };
 
@@ -66,8 +66,8 @@ class IPC_EXPORT Channel : public Endpoint {
     MODE_NAMED_SERVER = MODE_SERVER_FLAG | MODE_NAMED_FLAG,
     MODE_NAMED_CLIENT = MODE_CLIENT_FLAG | MODE_NAMED_FLAG,
 #if defined(OS_POSIX)
-    MODE_OPEN_NAMED_SERVER =
-        MODE_OPEN_ACCESS_FLAG | MODE_SERVER_FLAG | MODE_NAMED_FLAG
+    MODE_OPEN_NAMED_SERVER = MODE_OPEN_ACCESS_FLAG | MODE_SERVER_FLAG |
+                             MODE_NAMED_FLAG
 #endif
   };
 
@@ -195,9 +195,9 @@ class IPC_EXPORT Channel : public Endpoint {
   // threads. This is constant for the lifetime of the |Channel|.
   virtual bool IsSendThreadSafe() const;
 
-// NaCl in Non-SFI mode runs on Linux directly, and the following functions
-// compiled on Linux are also needed. Please see also comments in
-// components/nacl_nonsfi.gyp for more details.
+  // NaCl in Non-SFI mode runs on Linux directly, and the following functions
+  // compiled on Linux are also needed. Please see also comments in
+  // components/nacl_nonsfi.gyp for more details.
 #if defined(OS_POSIX) && !defined(OS_NACL_SFI)
   // On POSIX an IPC::Channel wraps a socketpair(), this method returns the
   // FD # for the client end of the socket.
@@ -240,26 +240,6 @@ class IPC_EXPORT Channel : public Endpoint {
   // process such that it acts similar to if it was exec'd, for tests.
   static void NotifyProcessForkedForTesting();
 #endif
-
- protected:
-  // An OutputElement is a wrapper around a Message or raw buffer while it is
-  // waiting to be passed to the system's underlying IPC mechanism.
-  class OutputElement {
-   public:
-    // Takes ownership of message.
-    OutputElement(Message* message);
-    // Takes ownership of the buffer.
-    OutputElement(void* buffer, size_t length);
-    ~OutputElement();
-    size_t size() const;
-    const void* data() const;
-    const Message* get_message() const { return message_.get(); }
-
-   private:
-    scoped_ptr<const Message> message_;
-    void* buffer_;
-    size_t length_;
-  };
 };
 
 #if defined(OS_POSIX)