[MBI] Stop consulting RenderProcessHost/RenderThread on IPC listener lookup.

All listeners should be registered on the AgentSchedulingGroup(Host), so
there shouldn't be a need for this delegation.
This follows-up on a comment from crrev.com/c/2513958.

Bug: 1111231
Change-Id: I69e13cbc1cadd1c7d2dc7b5b425353adabd4c364
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2526667
Commit-Queue: Tal Pressman <talp@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Dominic Farolino <dom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826602}

content/browser/renderer_host/agent_scheduling_group_host.cc

@@ -7,12 +7,12 @@
 
 #include "base/feature_list.h"
 #include "base/supports_user_data.h"
-#include "base/util/type_safety/pass_key.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/common/agent_scheduling_group.mojom.h"
 #include "content/common/renderer.mojom.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/content_features.h"
+#include "ipc/ipc_message.h"
 
 namespace content {
 
@@ -29,8 +29,6 @@ using ::mojo::PendingRemote;
 using ::mojo::Receiver;
 using ::mojo::Remote;
 
-using PassKey = ::util::PassKey<AgentSchedulingGroupHost>;
-
 static constexpr char kAgentGroupHostDataKey[] =
     "AgentSchedulingGroupHostUserDataKey";
 
@@ -49,10 +47,6 @@ class AgentGroupHostUserData : public base::SupportsUserData::Data {
   std::unique_ptr<AgentSchedulingGroupHost> agent_group_;
 };
 
-RenderProcessHostImpl& ToImpl(RenderProcessHost& process) {
-  return static_cast<RenderProcessHostImpl&>(process);
-}
-
 }  // namespace
 
 // MaybeAssociatedReceiver:
@@ -349,15 +343,9 @@ void AgentSchedulingGroupHost::SetUpMojoIfNeeded() {
 }
 
 Listener* AgentSchedulingGroupHost::GetListener(int32_t routing_id) {
-  if (routing_id == MSG_ROUTING_CONTROL)
-    return &process_;
-
-  if (auto* listener = listener_map_.Lookup(routing_id))
-    return listener;
+  DCHECK_NE(routing_id, MSG_ROUTING_CONTROL);
 
-  // TODO(crbug.com/1111231): Can/should we log it when we find the listener on
-  // the process but not here?
-  return ToImpl(process_).GetListener(PassKey(), routing_id);
+  return listener_map_.Lookup(routing_id);
 }
 
 }  // namespace content

content/browser/renderer_host/render_process_host_impl.cc

@@ -2526,12 +2526,6 @@ void RenderProcessHostImpl::RegisterMojoInterfaces() {
       std::move(registry), std::move(child_host_pending_receiver_));
 }
 
-IPC::Listener* RenderProcessHostImpl::GetListener(
-    util::PassKey<AgentSchedulingGroupHost>,
-    int32_t routing_id) {
-  return listeners_.Lookup(routing_id);
-}
-
 void RenderProcessHostImpl::CreateEmbeddedFrameSinkProvider(
     mojo::PendingReceiver<blink::mojom::EmbeddedFrameSinkProvider> receiver) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);

content/browser/renderer_host/render_process_host_impl.h

@@ -762,12 +762,6 @@ class CONTENT_EXPORT RenderProcessHostImpl
   // Registers Mojo interfaces to be exposed to the renderer.
   void RegisterMojoInterfaces();
 
-  // TODO(crbug.com/1132901): We'll be able to remove this method once
-  // `AgentSchedulingGroupHost` maintains its own map of IPC::Listeners, but for
-  // now we'll let it delegate to this class.
-  IPC::Listener* GetListener(util::PassKey<AgentSchedulingGroupHost>,
-                             int32_t routing_id);
-
   // mojom::RendererHost
   using BrowserHistogramCallback =
       mojom::RendererHost::GetBrowserHistogramCallback;

content/child/child_thread_impl.cc

@@ -843,8 +843,4 @@ bool ChildThreadImpl::IsInBrowserProcess() const {
   return static_cast<bool>(browser_process_io_runner_);
 }
 
-IPC::Listener* ChildThreadImpl::GetListener(int32_t routing_id) {
-  return router_.GetRoute(routing_id);
-}
-
 }  // namespace content

content/child/child_thread_impl.h

@@ -161,11 +161,6 @@ class CONTENT_EXPORT ChildThreadImpl : public IPC::Listener,
 
   bool IsInBrowserProcess() const;
 
-  // TODO(1132901) We'll be able to move this method once |AgentSchedulingGroup|
-  // maintains its own map of IPC::Listeners, but for now we'll let it delegate
-  // to this class.
-  virtual IPC::Listener* GetListener(int32_t routing_id);
-
  private:
   // TODO(crbug.com/1111231): This class is a friend so that it can call our
   // private mojo implementation methods, acting as a pass-through. This is only

content/renderer/agent_scheduling_group.cc

@@ -234,15 +234,9 @@ void AgentSchedulingGroup::GetAssociatedInterface(
 }
 
 Listener* AgentSchedulingGroup::GetListener(int32_t routing_id) {
-  if (routing_id == MSG_ROUTING_CONTROL)
-    return &ToImpl(render_thread_);
+  DCHECK_NE(routing_id, MSG_ROUTING_CONTROL);
 
-  if (auto* listener = listener_map_.Lookup(routing_id))
-    return listener;
-
-  // TODO(crbug.com/1111231): Can/should we log it when we find the listener on
-  // the render thread but not here?
-  return ToImpl(render_thread_).GetListener(routing_id);
+  return listener_map_.Lookup(routing_id);
 }
 
 }  // namespace content