Change memory dumps to not use periodic dumps by default.

base/trace_event/trace_config_unittest.cc

Index: base/trace_event/trace_config_unittest.cc
diff --git a/base/trace_event/trace_config_unittest.cc b/base/trace_event/trace_config_unittest.cc
index 57c36dc1497a4b90d4414db6d56d1b3276c2d307..7637701182c197c6d00cf405d86b7c5016990491 100644
--- a/base/trace_event/trace_config_unittest.cc
+++ b/base/trace_event/trace_config_unittest.cc
@@ -697,7 +697,7 @@ TEST(TraceConfigTest, LegacyStringToMemoryDumpConfig) {
   TraceConfig tc(MemoryDumpManager::kTraceCategory, "");
   EXPECT_TRUE(tc.IsCategoryGroupEnabled(MemoryDumpManager::kTraceCategory));
   EXPECT_NE(std::string::npos, tc.ToString().find("memory_dump_config"));
-  EXPECT_EQ(1u, tc.memory_dump_config().triggers.size());
+  EXPECT_EQ(0u, tc.memory_dump_config().triggers.size());
   EXPECT_EQ(
       TraceConfig::MemoryDumpConfig::HeapProfiler ::
           kDefaultBreakdownThresholdBytes,