Change memory dumps to not use periodic dumps by default.

content/browser/tracing/tracing_ui.cc

Index: content/browser/tracing/tracing_ui.cc
diff --git a/content/browser/tracing/tracing_ui.cc b/content/browser/tracing/tracing_ui.cc
index 14389658a420ecb7b3f5d00d287fedeabee87753..ac40d50c355341dc6a30669fc98e56e57d900a84 100644
--- a/content/browser/tracing/tracing_ui.cc
+++ b/content/browser/tracing/tracing_ui.cc
@@ -89,6 +89,21 @@ bool GetTracingOptions(const std::string& data64,
   *trace_config = base::trace_event::TraceConfig(category_filter_string,
                                                  record_mode);
 
+  // When enabling memory-infra via tracing, use periodic dumping to trigger a
+  // detailed dump every 5s.
+  if (trace_config->category_filter().IsCategoryEnabled(

[ssid, 2017/05/26 21:56:07]

This should just be trace/config->IsCategoryGroupEnabled
In future if we change memory-infra to be default category (no
disabled-by-default) then this function will still return false but the other
will return true. In general this api (category_filter()) should not be exposed.
This should be fixed, seems to be used only in tests.

[erikchen, 2017/05/27 00:51:03]

Done.

+          base::trace_event::MemoryDumpManager::kTraceCategory)) {
+    base::trace_event::TraceConfig::MemoryDumpConfig::Trigger trigger = {
+        5000,  // min_time_between_dumps_ms
+        base::trace_event::MemoryDumpLevelOfDetail::DETAILED,
+        base::trace_event::MemoryDumpType::PERIODIC_INTERVAL};
+    base::trace_event::TraceConfig::MemoryDumpConfig memory_dump_config;
+    memory_dump_config.triggers.push_back(trigger);
+    memory_dump_config.allowed_dump_modes.insert(
+        base::trace_event::MemoryDumpLevelOfDetail::DETAILED);
+    trace_config->ResetMemoryDumpConfig(memory_dump_config);
+  }
+
   bool enable_systrace;
   options_ok &= options->GetBoolean("useSystemTracing", &enable_systrace);
   if (enable_systrace)