Adds Channel-associated interface support on ChannelProxy's thread

ipc/ipc_mojo_bootstrap.cc

Index: ipc/ipc_mojo_bootstrap.cc
diff --git a/ipc/ipc_mojo_bootstrap.cc b/ipc/ipc_mojo_bootstrap.cc
index 425f794858f02732f6ccf5736f51c0fcfadfb84f..e84e4e528a5010d97548800680a6774c7ef64c0b 100644
--- a/ipc/ipc_mojo_bootstrap.cc
+++ b/ipc/ipc_mojo_bootstrap.cc
@@ -442,7 +442,6 @@ class ChannelAssociatedGroupController
       // If the client is not yet bound, it must be bound by the time this task
       // runs or else it's programmer error.
       DCHECK(proxy_task_runner_);
-      CHECK(false);

[Ken Rockot(use gerrit already), 2016/07/13 22:56:25]

Forgot to remove this on the last CL. :o

       std::unique_ptr<mojo::Message> passed_message(new mojo::Message);
       message->MoveTo(passed_message.get());
       proxy_task_runner_->PostTask(
@@ -471,8 +470,34 @@ class ChannelAssociatedGroupController
   void AcceptOnProxyThread(std::unique_ptr<mojo::Message> message) {
     DCHECK(proxy_task_runner_->BelongsToCurrentThread());
 
-    // TODO(rockot): Implement this.
-    NOTREACHED();
+    mojo::InterfaceId id = message->interface_id();
+    DCHECK(mojo::IsValidInterfaceId(id) && !mojo::IsMasterInterfaceId(id));
+
+    base::AutoLock locker(lock_);
+    bool inserted = false;
+    Endpoint* endpoint = FindOrInsertEndpoint(id, &inserted);
+
+    // The endpoint must have already been inserted by Accept(), and if the

[yzshen1, 2016/07/13 23:25:09]

It seems to be possible that |inserted| is true. Imagine:
1) a task to posted to handle a message on the proxy thread;
2) the corresponding local endpoint is closed;
3) the controller is shutdown on the IO thread, peer_closed is set for all
endpoints so the endpoints already marked as closed will be removed from the
registry.
4) the task of (1) is handled on the proxy thread.

WDYT?

[Ken Rockot(use gerrit already), 2016/07/14 00:39:09]

Ah your right, I had convinced myself that #2 was impossible, but it can happen.
Fixed.

+    // system is behaving as intended and consumers are well-behaved, it should
+    // be impossible for the endpoint to have been removed yet.
+    DCHECK(!inserted);
+
+    mojo::InterfaceEndpointClient* client = endpoint->client();
+    DCHECK(client);

[yzshen1, 2016/07/13 23:25:09]

The local endpoint could already be detached, right? (The associated interface
ptr/binding is already gone)

[Ken Rockot(use gerrit already), 2016/07/14 00:39:09]

Indeed. Done.

+    DCHECK(endpoint->task_runner()->BelongsToCurrentThread());
+
+    // TODO(rockot): Implement sync dispatch. For now, sync messages are
+    // unsupported here.
+    DCHECK(!message->has_flag(mojo::Message::kFlagIsSync));
+
+    bool result = false;
+    {
+      base::AutoUnlock unlocker(lock_);
+      result = client->HandleIncomingMessage(message.get());
+    }
+
+    if (!result)
+      RaiseError();
   }
 
   // mojo::PipeControlMessageHandlerDelegate:
@@ -561,6 +586,11 @@ class BootstrapMasterProxy {
     return controller_->associated_group();
   }
 
+  ChannelAssociatedGroupController* controller() {
+    DCHECK(controller_);
+    return controller_.get();
+  }
+
   mojom::Bootstrap* operator->() {
     DCHECK(proxy_);
     return proxy_.get();
@@ -596,6 +626,11 @@ class BootstrapMasterBinding {
     return controller_->associated_group();
   }
 
+  ChannelAssociatedGroupController* controller() {
+    DCHECK(controller_);
+    return controller_.get();
+  }
+
   void Bind(mojo::ScopedMessagePipeHandle handle) {
     DCHECK(!controller_);
     controller_ =
@@ -626,10 +661,16 @@ class MojoServerBootstrap : public MojoBootstrap {
  private:
   // MojoBootstrap implementation.
   void Connect() override;
+
   mojo::AssociatedGroup* GetAssociatedGroup() override {
     return bootstrap_.associated_group();
   }
 
+  void SetProxyTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner) override {
+    bootstrap_.controller()->SetProxyTaskRunner(task_runner);
+  }
+
   void OnInitDone(int32_t peer_pid);
 
   BootstrapMasterProxy bootstrap_;
@@ -688,10 +729,16 @@ class MojoClientBootstrap : public MojoBootstrap, public mojom::Bootstrap {
  private:
   // MojoBootstrap implementation.
   void Connect() override;
+
   mojo::AssociatedGroup* GetAssociatedGroup() override {
     return binding_.associated_group();
   }
 
+  void SetProxyTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner) override {
+    binding_.controller()->SetProxyTaskRunner(task_runner);
+  }
+
   // mojom::Bootstrap implementation.
   void Init(mojom::ChannelAssociatedRequest receive_channel,
             mojom::ChannelAssociatedPtrInfo send_channel,