[memory-infra] Add api to enable heap profiling in MemoryDumpManager

base/trace_event/memory_dump_manager.h

Index: base/trace_event/memory_dump_manager.h
diff --git a/base/trace_event/memory_dump_manager.h b/base/trace_event/memory_dump_manager.h
index ebee048691628d5c29201eadd9efe17fe5032349..73efcc37528c86f9847d7b7763de58c7da46c495 100644
--- a/base/trace_event/memory_dump_manager.h
+++ b/base/trace_event/memory_dump_manager.h
@@ -126,6 +126,10 @@ class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
   // Enable heap profiling if kEnableHeapProfiling is specified.
   void EnableHeapProfilingIfNeeded();
 
+  // Enable heap profiling with specified |capture_mode|. Disabling heap
+  // profiler will disable it permanently and cannot be enabled again.
+  void EnableHeapProfiling(AllocationContextTracker::CaptureMode capture_mode);
+
   // Returns true if the dump mode is allowed for current tracing session.
   bool IsDumpModeAllowed(MemoryDumpLevelOfDetail dump_mode);
 
@@ -346,6 +350,10 @@ class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
   void UnregisterPollingMDPOnDumpThread(
       scoped_refptr<MemoryDumpProviderInfo> mdpinfo);
 
+  // Helper to enable heap profiling.
+  void EnableHeapProfilingLocked(
+      AllocationContextTracker::CaptureMode capture_mode);
+
   // An ordererd set of registered MemoryDumpProviderInfo(s), sorted by task
   // runner affinity (MDPs belonging to the same task runners are adjacent).
   MemoryDumpProviderInfo::OrderedSet dump_providers_;
@@ -383,8 +391,11 @@ class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
   // When true, calling |RegisterMemoryDumpProvider| is a no-op.
   bool dumper_registrations_ignored_for_testing_;
 
-  // Whether new memory dump providers should be told to enable heap profiling.
-  bool heap_profiling_enabled_;
+  // Heap profiling can be enabled and disabled only once in the process.
+  // New memory dump providers should be told to enable heap profiling if state
+  // is ENABLED.
+  enum class HeapProfilingState { DISABLED, ENABLED, DISABLED_PERMANENTLY };
+  HeapProfilingState heap_profiling_state_;
 
   DISALLOW_COPY_AND_ASSIGN(MemoryDumpManager);
 };