memory-infra: Start disentangling tracing from memory-infra

base/trace_event/memory_dump_manager.cc

Index: base/trace_event/memory_dump_manager.cc
diff --git a/base/trace_event/memory_dump_manager.cc b/base/trace_event/memory_dump_manager.cc
index 7e62064ec6a08e25fcdbc0f79cb3065ed36b1e4a..beb8ceb1b2c5757c5ef92bbec3d7b4d9959a61fd 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -35,6 +35,7 @@
 #include "base/trace_event/memory_dump_session_state.h"
 #include "base/trace_event/memory_infra_background_whitelist.h"
 #include "base/trace_event/memory_peak_detector.h"
+#include "base/trace_event/memory_tracing_frontend.h"

[ssid, 2017/04/14 23:33:09]

Feels like this dependency shouldn't exist?

[hjd, 2017/04/19 09:54:56]

Acknowledged. See message.

 #include "base/trace_event/process_memory_dump.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ -198,7 +199,6 @@ MemoryDumpManager::MemoryDumpManager()
 }
 
 MemoryDumpManager::~MemoryDumpManager() {
-  TraceLog::GetInstance()->RemoveEnabledStateObserver(this);
 }
 
 void MemoryDumpManager::EnableHeapProfilingIfNeeded() {
@@ -288,15 +288,6 @@ void MemoryDumpManager::Initialize(
     TraceLog::GetInstance()->SetEnabled(filtering_trace_config,
                                         TraceLog::FILTERING_MODE);
   }
-
-  // If tracing was enabled before initializing MemoryDumpManager, we missed the
-  // OnTraceLogEnabled() event. Synthetize it so we can late-join the party.
-  // IsEnabled is called before adding observer to avoid calling
-  // OnTraceLogEnabled twice.
-  bool is_tracing_already_enabled = TraceLog::GetInstance()->IsEnabled();
-  TraceLog::GetInstance()->AddEnabledStateObserver(this);
-  if (is_tracing_already_enabled)
-    OnTraceLogEnabled();
 }
 
 void MemoryDumpManager::RegisterDumpProvider(
@@ -792,14 +783,6 @@ void MemoryDumpManager::FinalizeDumpAndAddToTrace(
     }
   }
 
-  bool tracing_still_enabled;
-  TRACE_EVENT_CATEGORY_GROUP_ENABLED(kTraceCategory, &tracing_still_enabled);
-  if (!tracing_still_enabled) {
-    pmd_async_state->dump_successful = false;
-    VLOG(1) << kLogPrefix << " failed because tracing was disabled before"
-            << " the dump was completed";
-  }

[hjd, 2017/04/13 14:16:59]

Can we just remove this now?

[ssid, 2017/04/14 23:33:09]

I think this can be removed along with
TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_PROCESS_ID.
As long as we have this event here this should logically stay here?

[hjd, 2017/04/19 09:54:56]

Okay, I've moved TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_PROCESS_ID onto it's own
static method on MemoryTracingObserver!

-
   if (!pmd_async_state->callback.is_null()) {
     pmd_async_state->callback.Run(dump_guid, pmd_async_state->dump_successful);
     pmd_async_state->callback.Reset();
@@ -809,12 +792,7 @@ void MemoryDumpManager::FinalizeDumpAndAddToTrace(
                                   TRACE_ID_LOCAL(dump_guid));
 }
 
-void MemoryDumpManager::OnTraceLogEnabled() {
-  bool enabled;
-  TRACE_EVENT_CATEGORY_GROUP_ENABLED(kTraceCategory, &enabled);
-  if (!enabled)
-    return;
-
+void MemoryDumpManager::Enable() {
   // Initialize the TraceLog for the current thread. This is to avoid that the
   // TraceLog memory dump provider is registered lazily in the PostTask() below
   // while the |lock_| is taken;
@@ -915,7 +893,7 @@ void MemoryDumpManager::OnTraceLogEnabled() {
   }
 }
 
-void MemoryDumpManager::OnTraceLogDisabled() {
+void MemoryDumpManager::Disable() {
   // There might be a memory dump in progress while this happens. Therefore,
   // ensure that the MDM state which depends on the tracing enabled / disabled
   // state is always accessed by the dumping methods holding the |lock_|.