WIP: The tracing service prototype

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..29402c9b9d098d3a3454a44904a45af04ea4bf27 100644
--- a/services/resource_coordinator/public/interfaces/tracing/tracing.mojom
+++ b/services/resource_coordinator/public/interfaces/tracing/tracing.mojom
@@ -20,21 +20,25 @@ 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,
+interface AgentSet {
+  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);
+  // If |report_categories_only| is true, the agent should not send trace events
+  // to the recorder; they will be ignored; it should send only the list of
+  // categories known to the agent.
+  StartTracing(
+      string config, Recorder recorder, bool report_categories_only) => ();
   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);
 };
 
@@ -43,6 +47,7 @@ interface Agent {
 // There should be only one agent of type STRING per agent label; otherwise
 // their trace data would be mixed up.
 interface Recorder {
+  AddCategories(string categories);
   AddChunk(string chunk);
   AddMetadata(mojo.common.mojom.DictionaryValue metadata);
 };
@@ -51,8 +56,10 @@ interface Recorder {
 // from all registered agents. At any given time, there should be at most one
 // connected controller.
 interface Coordinator {
-  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);
 };