Reland of "[memory-infra] Add unittests for peak detection and NotifyDumpTriggered"

base/trace_event/memory_dump_scheduler.h

Index: base/trace_event/memory_dump_scheduler.h
diff --git a/base/trace_event/memory_dump_scheduler.h b/base/trace_event/memory_dump_scheduler.h
index fd21fce834949be99aa386a1e12362a103368d48..4cf0fd0b1585091fb56d11a44f52e17a488e6a47 100644
--- a/base/trace_event/memory_dump_scheduler.h
+++ b/base/trace_event/memory_dump_scheduler.h
@@ -50,10 +50,12 @@ class BASE_EXPORT MemoryDumpScheduler {
 
  private:
   friend class MemoryDumpManagerTest;
+  friend class MemoryDumpSchedulerPollingTest;
   FRIEND_TEST_ALL_PREFIXES(MemoryDumpManagerTest, TestPollingOnDumpThread);
+  FRIEND_TEST_ALL_PREFIXES(MemoryDumpSchedulerPollingTest, NotifyDumpTriggered);
 
   // Helper class to schdule periodic memory dumps.
-  struct PeriodicTriggerState {
+  struct BASE_EXPORT PeriodicTriggerState {
     PeriodicTriggerState();
     ~PeriodicTriggerState();
 
@@ -71,7 +73,7 @@ class BASE_EXPORT MemoryDumpScheduler {
     DISALLOW_COPY_AND_ASSIGN(PeriodicTriggerState);
   };
 
-  struct PollingTriggerState {
+  struct BASE_EXPORT PollingTriggerState {
     enum State {
       CONFIGURED,  // Polling trigger was added.
       ENABLED,     // Polling is running.