Perfetto: Make ProducerClient a leaky singleton

This is needed as the TraceWriters we create and keep in TLS
keep a reference to the SharedMemoryArbiter object that the
ProducerClient keeps, and during shutdown may still be
used after the ProducerClient previously got deleted.

R=hjd@chromium.org
BUG=844379

Change-Id: Ib27b59b48ce50f88f954618e7eee4f046b3029b7
Reviewed-on: https://chromium-review.googlesource.com/1117776Reviewed-by: Hector Dearman <hjd@chromium.org>
Commit-Queue: oysteine <oysteine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571140}

services/tracing/perfetto/perfetto_integration_unittest.cc

@@ -292,7 +292,7 @@ TEST_F(PerfettoIntegrationTest, ProducerDatasourceInitialized) {
 
   producer_initialized_runloop.Run();
 
-  ProducerClient::DeleteSoon(std::move(dummy_client));
+  ProducerClient::DeleteSoonForTesting(std::move(dummy_client));
 }
 
 TEST_F(PerfettoIntegrationTest, ClientEnabledAndDisabled) {
@@ -327,7 +327,7 @@ TEST_F(PerfettoIntegrationTest, ClientEnabledAndDisabled) {
   on_trace_packets.Run();
   EXPECT_EQ(0u, consumer.received_packets());
 
-  ProducerClient::DeleteSoon(std::move(client));
+  ProducerClient::DeleteSoonForTesting(std::move(client));
 }
 
 TEST_F(PerfettoIntegrationTest, PacketsEndToEndProducerFirst) {
@@ -365,7 +365,7 @@ TEST_F(PerfettoIntegrationTest, PacketsEndToEndProducerFirst) {
 
   EXPECT_EQ(kNumPackets, consumer.received_packets());
 
-  ProducerClient::DeleteSoon(std::move(client));
+  ProducerClient::DeleteSoonForTesting(std::move(client));
 }
 
 TEST_F(PerfettoIntegrationTest, PacketsEndToEndConsumerFirst) {
@@ -400,7 +400,7 @@ TEST_F(PerfettoIntegrationTest, PacketsEndToEndConsumerFirst) {
   no_more_packets_runloop.Run();
 
   EXPECT_EQ(kNumPackets, consumer.received_packets());
-  ProducerClient::DeleteSoon(std::move(client));
+  ProducerClient::DeleteSoonForTesting(std::move(client));
 }
 
 #if defined(THREAD_SANITIZER)
@@ -444,7 +444,7 @@ TEST_F(PerfettoIntegrationTest, MAYBE_CommitDataRequestIsMaybeComplete) {
   EXPECT_EQ(client->all_client_commit_data_requests(),
             new_producer->all_host_commit_data_requests());
 
-  ProducerClient::DeleteSoon(std::move(client));
+  ProducerClient::DeleteSoonForTesting(std::move(client));
 }
 
 TEST_F(PerfettoIntegrationTest, TracingRestarted) {
@@ -501,7 +501,7 @@ TEST_F(PerfettoIntegrationTest, TracingRestarted) {
 
   EXPECT_EQ(kNumPackets * 2, consumer.received_packets());
 
-  ProducerClient::DeleteSoon(std::move(client));
+  ProducerClient::DeleteSoonForTesting(std::move(client));
 }
 
 TEST_F(PerfettoIntegrationTest, NoPacketsReceivedOnWrongSourceName) {
@@ -538,7 +538,7 @@ TEST_F(PerfettoIntegrationTest, NoPacketsReceivedOnWrongSourceName) {
   no_more_packets_runloop.Run();
 
   EXPECT_EQ(0u, consumer.received_packets());
-  ProducerClient::DeleteSoon(std::move(client));
+  ProducerClient::DeleteSoonForTesting(std::move(client));
 }
 
 TEST_F(PerfettoIntegrationTest,
@@ -572,8 +572,8 @@ TEST_F(PerfettoIntegrationTest,
   EXPECT_TRUE(client2->shared_memory());
   EXPECT_NE(client1->shared_memory(), client2->shared_memory());
 
-  ProducerClient::DeleteSoon(std::move(client1));
-  ProducerClient::DeleteSoon(std::move(client2));
+  ProducerClient::DeleteSoonForTesting(std::move(client1));
+  ProducerClient::DeleteSoonForTesting(std::move(client2));
 }
 
 }  // namespace

services/tracing/public/cpp/perfetto/producer_client.cc

@@ -42,7 +42,7 @@ ProducerClient::~ProducerClient() {
 }
 
 // static
-void ProducerClient::DeleteSoon(
+void ProducerClient::DeleteSoonForTesting(
     std::unique_ptr<ProducerClient> producer_client) {
   GetTaskRunner()->DeleteSoon(FROM_HERE, std::move(producer_client));
 }

services/tracing/public/cpp/perfetto/producer_client.h

@@ -44,7 +44,7 @@ class COMPONENT_EXPORT(TRACING_CPP) ProducerClient
   ProducerClient();
   ~ProducerClient() override;
 
-  static void DeleteSoon(std::unique_ptr<ProducerClient>);
+  static void DeleteSoonForTesting(std::unique_ptr<ProducerClient>);
 
   // Returns the taskrunner used by Perfetto.
   static base::SequencedTaskRunner* GetTaskRunner();

services/tracing/public/cpp/trace_event_agent.cc

@@ -11,6 +11,7 @@
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_memory.h"
+#include "base/no_destructor.h"
 #include "base/strings/string_util.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
@@ -35,14 +36,23 @@ const char kTraceEventLabel[] = "traceEvents";
 namespace tracing {
 
 #if defined(PERFETTO_AVAILABLE)
+
+namespace {
+
+ProducerClient* GetProducerClient() {
+  static base::NoDestructor<ProducerClient> producer_client;
+  return producer_client.get();
+}
+
+}  // namespace
+
 class PerfettoTraceEventAgent : public TraceEventAgent {
  public:
   explicit PerfettoTraceEventAgent(service_manager::Connector* connector) {
     mojom::PerfettoServicePtr perfetto_service;
     connector->BindInterface(mojom::kServiceName, &perfetto_service);
 
-    producer_client_ = std::make_unique<ProducerClient>();
-    producer_client_->CreateMojoMessagepipes(base::BindOnce(
+    GetProducerClient()->CreateMojoMessagepipes(base::BindOnce(
         [](mojom::PerfettoServicePtr perfetto_service,
            mojom::ProducerClientPtr producer_client_pipe,
            mojom::ProducerHostRequest producer_host_pipe) {
@@ -51,13 +61,6 @@ class PerfettoTraceEventAgent : public TraceEventAgent {
         },
         std::move(perfetto_service)));
   }
-
-  ~PerfettoTraceEventAgent() override {
-    ProducerClient::DeleteSoon(std::move(producer_client_));
-  }
-
- private:
-  std::unique_ptr<ProducerClient> producer_client_;
 };
 #endif