[tracing] Introduce "allowed_dump_modes" for memory dump config

content/browser/tracing/background_tracing_manager_impl.cc

Index: content/browser/tracing/background_tracing_manager_impl.cc
diff --git a/content/browser/tracing/background_tracing_manager_impl.cc b/content/browser/tracing/background_tracing_manager_impl.cc
index 610b01881c2570af6b78c2ead730d16f4c2d7571..536624022f28758557e30fe643acbf22a8c0e24a 100644
--- a/content/browser/tracing/background_tracing_manager_impl.cc
+++ b/content/browser/tracing/background_tracing_manager_impl.cc
@@ -47,8 +47,6 @@ void RecordBackgroundTracingMetric(BackgroundTracingMetrics metric) {
 }
 
 // Tracing enabled callback for BENCHMARK_MEMORY_LIGHT category preset.
-// TODO(ssid): Remove this when background tracing supports trace config strings
-// and memory-infra supports peak detection crbug.com/609935.
 void BenchmarkMemoryLight_TracingEnabledCallback() {
   base::trace_event::MemoryDumpManager::GetInstance()->RequestGlobalDump(
       base::trace_event::MemoryDumpType::EXPLICITLY_TRIGGERED,
@@ -409,6 +407,12 @@ void BackgroundTracingManagerImpl::StartTracing(
                            BENCHMARK_MEMORY_LIGHT) {
     // On memory light mode, the periodic memory dumps are disabled and a single
     // memory dump is requested after tracing is enabled in all the processes.
+    // TODO(ssid): Remove this when background tracing supports trace config
+    // strings and memory-infra supports peak detection crbug.com/609935.
+    base::trace_event::TraceConfig::MemoryDumpConfig memory_config;
+    memory_config.allowed_dump_modes =
+        std::set<base::trace_event::MemoryDumpLevelOfDetail>(
+            {base::trace_event::MemoryDumpLevelOfDetail::BACKGROUND});
     trace_config.ResetMemoryDumpConfig(
         base::trace_event::TraceConfig::MemoryDumpConfig());

[Primiano Tucci (use gerrit), 2016/06/09 18:46:39]

ehm don't you have to pass memory_config here instead? 
This is what I said where I worry that we forget to plumb the traceconfig fully.

Can we add a cross-check? In the BenchmarkMemoryLight_TracingEnabledCallback can
we 
if (preset == MEMORY_LIGHT)
CHEKCK_FALSE(MDM::GetInstance::IsDumpModeAllowed(DETAILED)) 

[ssid, 2016/06/09 21:34:15]

Done.
Yeah I think this should be fixed when we can have trace config uploaded from
finch. we will have better control.

     tracing_enabled_callback =