Fixed and re-enabled ProtoBackgroundTracingTest.ProtoTraceReceived

Also made the test a little bit more predictable.

Bug: 1008387
Change-Id: I652a1032b3442bbfeed1d16e75b251e55e675221
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1837071Reviewed-by: ssid <ssid@chromium.org>
Commit-Queue: oysteine <oysteine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702576}

content/browser/tracing/background_tracing_manager_browsertest.cc

@@ -1658,8 +1658,7 @@ IN_PROC_BROWSER_TEST_F(ProtoBackgroundTracingTest,
   background_tracing_helper.WaitForScenarioAborted();
 }
 
-// Flaky failures in all OSes: crbug.com/1008387
-IN_PROC_BROWSER_TEST_F(ProtoBackgroundTracingTest, DISABLED_ProtoTraceReceived) {
+IN_PROC_BROWSER_TEST_F(ProtoBackgroundTracingTest, ProtoTraceReceived) {
   TestBackgroundTracingHelper background_tracing_helper;
 
   std::unique_ptr<BackgroundTracingConfig> config = CreatePreemptiveConfig();
@@ -1670,10 +1669,12 @@ IN_PROC_BROWSER_TEST_F(ProtoBackgroundTracingTest, DISABLED_ProtoTraceReceived)
 
   EXPECT_TRUE(BackgroundTracingManager::GetInstance()->SetActiveScenario(
       std::move(config), base::DoNothing(),
-      BackgroundTracingManager::NO_DATA_FILTERING));
+      BackgroundTracingManager::ANONYMIZE_DATA));
 
   background_tracing_helper.WaitForTracingEnabled();
 
+  NavigateToURLBlockUntilNavigationsComplete(shell(), GURL("about:blank"), 1);
+
   TestTriggerHelper trigger_helper;
   BackgroundTracingManager::GetInstance()->TriggerNamedEvent(
       handle, trigger_helper.receive_closure(true));

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

@@ -99,16 +99,19 @@ perfetto::TraceConfig GetDefaultPerfettoConfig(
 
 // Capture system trace events if supported and enabled. The datasources will
 // only emit events if system tracing is enabled in |chrome_config|.
+  if (!privacy_filtering_enabled) {
 #if defined(OS_CHROMEOS) || (defined(IS_CHROMECAST) && defined(OS_LINUX))
-  AddDataSourceConfig(&perfetto_config,
-                      tracing::mojom::kSystemTraceDataSourceName,
-                      chrome_config_string, privacy_filtering_enabled);
+    AddDataSourceConfig(&perfetto_config,
+                        tracing::mojom::kSystemTraceDataSourceName,
+                        chrome_config_string, privacy_filtering_enabled);
 #endif
 
 #if defined(OS_CHROMEOS)
-  AddDataSourceConfig(&perfetto_config, tracing::mojom::kArcTraceDataSourceName,
-                      chrome_config_string, privacy_filtering_enabled);
+    AddDataSourceConfig(&perfetto_config,
+                        tracing::mojom::kArcTraceDataSourceName,
+                        chrome_config_string, privacy_filtering_enabled);
 #endif
+  }
 
   // Also capture global metadata.
   AddDataSourceConfig(&perfetto_config, tracing::mojom::kMetaDataSourceName,