Update ChannelReader to use AttachmentBroker.

Previously, translating from bytes into messages and dispatching the messages
was accomplished in a single step. I've split this into two steps. The function
TranslateInputData turns bytes into messages, and puts those messages in a
queue. The function DispatchMessages() dispatches messages from the queue.
Messages cannot be dispatched until all attachments have been brokered, so
DispatchMessages() will sometimes wait (asynchronously) for the attachments to
get brokered.

BUG=466437

Review URL: https://codereview.chromium.org/1206093002

Cr-Commit-Position: refs/heads/master@{#340509}

1 files changed, 13 insertions, 2 deletions

diff --git a/ipc/brokerable_attachment.cc b/ipc/brokerable_attachment.cc
index 764f2b2..9af40d9 100644
--- a/ipc/brokerable_attachment.cc
+++ b/ipc/brokerable_attachment.cc
@@ -21,10 +21,13 @@ BrokerableAttachment::AttachmentId GetRandomId() {
 
 }  // namespace
 
-BrokerableAttachment::BrokerableAttachment() : id_(GetRandomId()) {
+BrokerableAttachment::BrokerableAttachment()
+    : id_(GetRandomId()), needs_brokering_(false) {
 }
 
-BrokerableAttachment::BrokerableAttachment(const AttachmentId& id) : id_(id) {
+BrokerableAttachment::BrokerableAttachment(const AttachmentId& id,
+                                           bool needs_brokering)
+    : id_(id), needs_brokering_(needs_brokering) {
 }
 
 BrokerableAttachment::~BrokerableAttachment() {
@@ -34,6 +37,14 @@ BrokerableAttachment::AttachmentId BrokerableAttachment::GetIdentifier() const {
   return id_;
 }
 
+bool BrokerableAttachment::NeedsBrokering() const {
+  return needs_brokering_;
+}
+
+void BrokerableAttachment::SetNeedsBrokering(bool needs_brokering) {
+  needs_brokering_ = needs_brokering;
+}
+
 BrokerableAttachment::Type BrokerableAttachment::GetType() const {
   return TYPE_BROKERABLE_ATTACHMENT;
 }