memlog: Add task contexts from allocation context to native mode

The task context is useful to debug mojo memory leaks since IPC messages
are tagged with contexts

BUG=874530

Change-Id: Id59d016f963f41fdeda6af69b3c470f0101dbfe7
Reviewed-on: https://chromium-review.googlesource.com/1232683Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Siddhartha S <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593458}

base/trace_event/heap_profiler_allocation_context_tracker.cc

@@ -259,13 +259,7 @@ bool AllocationContextTracker::GetContextSnapshot(AllocationContext* ctx) {
 
   ctx->backtrace.frame_count = backtrace - std::begin(ctx->backtrace.frames);
 
-  // TODO(ssid): Fix crbug.com/594803 to add file name as 3rd dimension
-  // (component name) in the heap profiler and not piggy back on the type name.
-  if (!task_contexts_.empty()) {
-    ctx->type_name = task_contexts_.back();
-  } else {
-    ctx->type_name = nullptr;
-  }
+  ctx->type_name = TaskContext();
 
   return true;
 }

base/trace_event/heap_profiler_allocation_context_tracker.h

@@ -108,6 +108,11 @@ class BASE_EXPORT AllocationContextTracker {
   void PushCurrentTaskContext(const char* context);
   void PopCurrentTaskContext(const char* context);
 
+  // Returns most recent task context added by ScopedTaskExecutionTracker.
+  const char* TaskContext() const {
+    return task_contexts_.empty() ? nullptr : task_contexts_.back();
+  }
+
   // Fills a snapshot of the current thread-local context. Doesn't fill and
   // returns false if allocations are being ignored.
   bool GetContextSnapshot(AllocationContext* snapshot);

components/heap_profiling/test_driver.cc

@@ -901,8 +901,7 @@ bool TestDriver::ValidateBrowserAllocations(base::Value* dump_json) {
   if (IsRecordingAllAllocations()) {
     if (should_validate_dumps) {
       result = ValidateDump(heaps_v2, kMallocAllocSize * kMallocAllocCount,
-                            kMallocAllocCount, "malloc",
-                            HasPseudoFrames() ? kMallocTypeTag : nullptr,
+                            kMallocAllocCount, "malloc", kMallocTypeTag,
                             HasPseudoFrames() ? kMallocEvent : "", thread_name);
       if (!result) {
         LOG(ERROR) << "Failed to validate malloc fixed allocations";

components/services/heap_profiling/public/cpp/allocator_shim.cc

@@ -735,7 +735,8 @@ void InitAllocationRecorder(SenderPipe* sender_pipe,
       break;
     case mojom::StackMode::NATIVE_WITH_THREAD_NAMES:
     case mojom::StackMode::NATIVE_WITHOUT_THREAD_NAMES:
-      AllocationContextTracker::SetCaptureMode(CaptureMode::DISABLED);
+      // This would track task contexts only.
+      AllocationContextTracker::SetCaptureMode(CaptureMode::NATIVE_STACK);
       break;
   }
 
@@ -791,7 +792,8 @@ void SerializeFramesFromAllocationContext(FrameSerializer* serializer,
     *context = allocation_context.type_name;
 }
 
-void SerializeFramesFromBacktrace(FrameSerializer* serializer) {
+void SerializeFramesFromBacktrace(FrameSerializer* serializer,
+                                  const char** context) {
   // Skip 3 top frames related to the profiler itself, e.g.:
   //   base::debug::StackTrace::StackTrace
   //   heap_profiling::RecordAndSendAlloc
@@ -824,6 +826,13 @@ void SerializeFramesFromBacktrace(FrameSerializer* serializer) {
     const char* thread_name = GetOrSetThreadName();
     serializer->AddCString(thread_name);
   }
+
+  if (!*context) {
+    const auto* tracker =
+        AllocationContextTracker::GetInstanceForCurrentThread();
+    if (tracker)
+      *context = tracker->TaskContext();
+  }
 }
 
 void AllocatorShimLogAlloc(AllocatorType type,
@@ -895,7 +904,7 @@ void RecordAndSendAlloc(AllocatorType type,
       capture_mode == CaptureMode::MIXED_STACK) {
     SerializeFramesFromAllocationContext(&serializer, &context);
   } else {
-    SerializeFramesFromBacktrace(&serializer);
+    SerializeFramesFromBacktrace(&serializer, &context);
   }
 
   size_t context_len = context ? strnlen(context, kMaxContextLen) : 0;