tracing: the client lib of the tracing service

services/resource_coordinator/public/interfaces/tracing/tracing.mojom

Index: services/resource_coordinator/public/interfaces/tracing/tracing.mojom
diff --git a/services/resource_coordinator/public/interfaces/tracing/tracing.mojom b/services/resource_coordinator/public/interfaces/tracing/tracing.mojom
index fb8cd3cbac55e130bd256d99acf7e8df6844c50c..bdddac8e5a1fabebfb3fd62e6d4e7a59f22d93dc 100644
--- a/services/resource_coordinator/public/interfaces/tracing/tracing.mojom
+++ b/services/resource_coordinator/public/interfaces/tracing/tracing.mojom
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-module resource_coordinator.tracing.mojom;
+module tracing.mojom;
 
 import "mojo/common/time.mojom";
 import "mojo/common/values.mojom";
@@ -20,22 +20,29 @@ enum TraceDataType {
 
 // Tracing agents, like |chrome|, |etw|, |battor|, and |cros|, use this
 // interface to register themselves to the tracing service.
-interface Factory {
-  RegisterAgent(Agent agent, string name, string label, TraceDataType type,
+//
+// This is a separate interface from |Coordinator| for security and privacy
+// reasones: although we want to let almost every process be able to send

[kenrb, 2017/05/17 21:24:02]

nit: s/reasones/reasons

[chiniforooshan, 2017/05/17 21:33:17]

Done.

+// tracing data to the service, we do not want to let an untrusted child process
+// be able to collect traces from other processes using the |Coordinator|
+// interface.
+interface AgentRegistry {
+  RegisterAgent(Agent agent, string label, TraceDataType type,
                 bool supports_explicit_clock_sync_);
 };
 
-// There should be at most one implementation of this interface per process.
 // When the tracing service calls |StopAndFlush| on an agent, the agent begins
 // serializing data into the recorder that was given in the |StartTracing| call.
 // When finished, the agent should close the recorder connection to signal the
 // tracing service that no more data will be sent.
 interface Agent {
-  StartTracing(string categories, Recorder recorder);
+  StartTracing(string config, Recorder recorder) => ();
   StopAndFlush();
-  RequestClockSyncMarker() => (mojo.common.mojom.TimeTicks issue_ts,
-                               mojo.common.mojom.TimeTicks issue_end_ts);
+  RequestClockSyncMarker(string sync_id) => (
+      mojo.common.mojom.TimeTicks issue_ts,
+      mojo.common.mojom.TimeTicks issue_end_ts);
   RequestBufferStatus() => (uint32 capacity, uint32 count);
+  GetCategories() => (string categories);
 };
 
 // An agent can make several calls to |AddChunk|. Chunks will be concatenated
@@ -51,8 +58,10 @@ interface Recorder {
 // from all registered agents. At any given time, there should be at most one
 // connected controller.
 interface Coordinator {

[kenrb, 2017/05/17 21:24:02]

How do you prevent renderer processes from being able to connect to this
interface? I had a quick look through the prototype and couldn't see anything --
is the intent to add a ConnectionFilter?

[chiniforooshan, 2017/05/17 21:33:17]

Isn't it enough that we don't "provide" the Coordinator interface
to the renderer in the tracing service manifest or in
content/public/app/mojo/content_browser_manifest.json and only
provide the AgentRegistry interface?

[kenrb, 2017/05/18 02:19:52]

Yes, thanks, this is right, sorry about my confusion. More specifically, the
renderer manifest doesn't require the tracing capability, which is what the
service manager will check before allowing an interface to be bound.

[chiniforooshan, 2017/05/18 15:23:49]

Acknowledged.

-  StartTracing(handle<data_pipe_producer> stream, string categories);
+  StartTracing(handle<data_pipe_producer> stream, string config);
   StopAndFlush();
   IsTracing() => (bool is_tracing);
-  RequestBufferUsage() => (float percent_full, uint32 approximate_count);
+  RequestBufferUsage() => (bool success, float percent_full,
+                           uint32 approximate_count);
+  GetCategories() => (string categories);
 };