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

Review URL: https://codereview.chromium.org/1286253002

Cr-Commit-Position: refs/heads/master@{#344389}

1 files changed, 2 insertions, 15 deletions

diff --git a/ipc/handle_attachment_win.cc b/ipc/handle_attachment_win.cc
index 50e3e6d..b7f4373 100644
--- a/ipc/handle_attachment_win.cc
+++ b/ipc/handle_attachment_win.cc
@@ -14,13 +14,13 @@ HandleAttachmentWin::HandleAttachmentWin(const HANDLE& handle,
     : handle_(handle), permissions_(permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(const WireFormat& wire_format)
-    : BrokerableAttachment(wire_format.attachment_id, false),
+    : BrokerableAttachment(wire_format.attachment_id),
       handle_(LongToHandle(wire_format.handle)),
       permissions_(wire_format.permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(
     const BrokerableAttachment::AttachmentId& id)
-    : BrokerableAttachment(id, true),
+    : BrokerableAttachment(id),
       handle_(INVALID_HANDLE_VALUE),
       permissions_(HandleWin::INVALID) {}
 
@@ -32,19 +32,6 @@ HandleAttachmentWin::BrokerableType HandleAttachmentWin::GetBrokerableType()
   return WIN_HANDLE;
 }
 
-void HandleAttachmentWin::PopulateWithAttachment(
-    const BrokerableAttachment* attachment) {
-  DCHECK(NeedsBrokering());
-  DCHECK(!attachment->NeedsBrokering());
-  DCHECK(GetIdentifier() == attachment->GetIdentifier());
-  DCHECK_EQ(GetBrokerableType(), attachment->GetBrokerableType());
-
-  const HandleAttachmentWin* handle_attachment =
-      static_cast<const HandleAttachmentWin*>(attachment);
-  handle_ = handle_attachment->handle_;
-  SetNeedsBrokering(false);
-}
-
 HandleAttachmentWin::WireFormat HandleAttachmentWin::GetWireFormat(
     const base::ProcessId& destination) const {
   WireFormat format;