[tracing] Add thread name to the pseudo stack of heap profiler

base/trace_event/heap_profiler_allocation_context_tracker.cc

Index: base/trace_event/heap_profiler_allocation_context_tracker.cc
diff --git a/base/trace_event/heap_profiler_allocation_context_tracker.cc b/base/trace_event/heap_profiler_allocation_context_tracker.cc
index 2877d2af91b27ace28839ebaac7468322cf4823f..0aa54a84ed380f8ee7e8f669bd78532041943e14 100644
--- a/base/trace_event/heap_profiler_allocation_context_tracker.cc
+++ b/base/trace_event/heap_profiler_allocation_context_tracker.cc
@@ -49,12 +49,19 @@ AllocationContextTracker::GetInstanceForCurrentThread() {
   return tracker;
 }
 
-AllocationContextTracker::AllocationContextTracker() {
+AllocationContextTracker::AllocationContextTracker() : thread_name_(nullptr) {
   pseudo_stack_.reserve(kMaxStackDepth);
 }
 AllocationContextTracker::~AllocationContextTracker() {}
 
 // static
+void AllocationContextTracker::SetCurrentThreadName(const char* name) {
+  if (name && capture_enabled()) {
+    GetInstanceForCurrentThread()->thread_name_ = name;
+  }
+}
+
+// static
 void AllocationContextTracker::SetCaptureEnabled(bool enabled) {
   // When enabling capturing, also initialize the TLS slot. This does not create
   // a TLS instance yet.
@@ -103,6 +110,12 @@ AllocationContext AllocationContextTracker::GetContextSnapshot() {
     auto src_end = pseudo_stack_.end();
     auto dst_end = std::end(ctx.backtrace.frames);
 
+    // Add the thread name as the first enrty in the backtrace.
+    if (thread_name_) {
+      *dst = thread_name_;

[petrcermak, 2016/03/29 13:07:46]

I think that you should DCHECK that dst < dst_end here.

[ssid, 2016/03/29 18:19:11]

Done.

+      ++dst;
+    }
+
     // Copy as much of the bottom of the pseudo stack into the backtrace as
     // possible.
     for (; src != src_end && dst != dst_end; src++, dst++)