Document Pubsub usage

BUG=chromium:1113286
TEST=generate

Change-Id: Idae748570440802f55060c13e3806d7f21c1aa3c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2340509
Tested-by: Jacob Kopczynski <jkop@chromium.org>
Reviewed-by: Xinan Lin <linxinan@chromium.org>
Commit-Queue: Jacob Kopczynski <jkop@chromium.org>
Auto-Submit: Jacob Kopczynski <jkop@chromium.org>
diff --git a/go/test_platform/config/config.pb.go b/go/test_platform/config/config.pb.go
index 4ce6668..b3e66f9 100644
--- a/go/test_platform/config/config.pb.go
+++ b/go/test_platform/config/config.pb.go
@@ -29,8 +29,8 @@
 	Versioning          *Config_Versioning   `protobuf:"bytes,7,opt,name=versioning,proto3" json:"versioning,omitempty"`
 	TestRunner          *Config_TestRunner   `protobuf:"bytes,8,opt,name=test_runner,json=testRunner,proto3" json:"test_runner,omitempty"`
 	TestRunnerMigration *test_runner.Config  `protobuf:"bytes,9,opt,name=test_runner_migration,json=testRunnerMigration,proto3" json:"test_runner_migration,omitempty"`
-	// The PubSub topic, to which CTP sends build ID when the build starts
-	// and ends.
+	// Result flow topic: CTP publishes a message with build ID, once
+	// at build start and again at build end
 	Pubsub               *Config_PubSub `protobuf:"bytes,10,opt,name=pubsub,proto3" json:"pubsub,omitempty"`
 	XXX_NoUnkeyedLiteral struct{}       `json:"-"`
 	XXX_unrecognized     []byte         `json:"-"`
@@ -455,7 +455,7 @@
 // recipe.
 type Config_TestRunner struct {
 	Buildbucket *Config_Buildbucket `protobuf:"bytes,1,opt,name=buildbucket,proto3" json:"buildbucket,omitempty"`
-	// The PubSub topic to which Buildbucket sends the update of test runner build.
+	// Result flow topic: Publish a message for each build status update
 	Pubsub               *Config_PubSub `protobuf:"bytes,2,opt,name=pubsub,proto3" json:"pubsub,omitempty"`
 	XXX_NoUnkeyedLiteral struct{}       `json:"-"`
 	XXX_unrecognized     []byte         `json:"-"`
diff --git a/go/test_platform/request.pb.go b/go/test_platform/request.pb.go
index c873ced..14c2727 100644
--- a/go/test_platform/request.pb.go
+++ b/go/test_platform/request.pb.go
@@ -881,7 +881,13 @@
 // Notification defines parameters for the request to use to notify callers
 // of its test's status updates.
 type Request_Params_Notification struct {
-	// Pubsub topic to broadcast status updates to
+	// TODO(crbug.com/1113875): Swarming only allows 1 pubsub topic. We
+	// should create a common pubsub topic for all subscribers and replace
+	// this field with a map<string, string> that allows users to attach
+	// arbitrary attributes to the pubsub message.
+	// This will require API support from Swarming and/or BuildBucket.
+	//
+	// Pubsub topic to broadcast status updates to, for external listeners
 	PubsubTopic          string   `protobuf:"bytes,1,opt,name=pubsub_topic,json=pubsubTopic,proto3" json:"pubsub_topic,omitempty"`
 	XXX_NoUnkeyedLiteral struct{} `json:"-"`
 	XXX_unrecognized     []byte   `json:"-"`
diff --git a/src/test_platform/config/config.proto b/src/test_platform/config/config.proto
index 6ae8885..a0fc90f 100644
--- a/src/test_platform/config/config.proto
+++ b/src/test_platform/config/config.proto
@@ -72,7 +72,7 @@
     // recipe.
     message TestRunner {
         Buildbucket buildbucket = 1;
-        // The PubSub topic to which Buildbucket sends the update of test runner build.
+        // Result flow topic: Publish a message for each build status update
         PubSub pubsub = 2;
     }
 
@@ -88,7 +88,7 @@
 
     test_platform.migration.test_runner.Config test_runner_migration = 9;
 
-    // The PubSub topic, to which CTP sends build ID when the build starts
-    // and ends.
+    // Result flow topic: CTP publishes a message with build ID, once
+    // at build start and again at build end
     PubSub pubsub = 10;
 }
diff --git a/src/test_platform/request.proto b/src/test_platform/request.proto
index 33b47f1..5883b37 100644
--- a/src/test_platform/request.proto
+++ b/src/test_platform/request.proto
@@ -202,7 +202,13 @@
     // Notification defines parameters for the request to use to notify callers
     // of its test's status updates.
     message Notification {
-      // Pubsub topic to broadcast status updates to
+      // TODO(crbug.com/1113875): Swarming only allows 1 pubsub topic. We
+      // should create a common pubsub topic for all subscribers and replace
+      // this field with a map<string, string> that allows users to attach
+      // arbitrary attributes to the pubsub message.
+      // This will require API support from Swarming and/or BuildBucket.
+      //
+      // Pubsub topic to broadcast status updates to, for external listeners
       string pubsub_topic = 1;
     }