Revert of [tracing] Turn StackFrame into struct.

base/trace_event/heap_profiler_stack_frame_deduplicator.cc

Index: base/trace_event/heap_profiler_stack_frame_deduplicator.cc
diff --git a/base/trace_event/heap_profiler_stack_frame_deduplicator.cc b/base/trace_event/heap_profiler_stack_frame_deduplicator.cc
index 22957804f137b38b44f1610e6621c698702bbbd3..12121937530ff30503e6c6dd0a5f65cc38f4bedc 100644
--- a/base/trace_event/heap_profiler_stack_frame_deduplicator.cc
+++ b/base/trace_event/heap_profiler_stack_frame_deduplicator.cc
@@ -31,7 +31,7 @@
   std::map<StackFrame, int>* nodes = &roots_;
 
   // Loop through the frames, early out when a frame is null.
-  for (const StackFrame* it = beginFrame; it != endFrame; it++) {
+  for (const StackFrame* it = beginFrame; it != endFrame && *it; it++) {
     StackFrame frame = *it;
 
     auto node = nodes->find(frame);
@@ -78,19 +78,7 @@
     out->append(stringify_buffer);
 
     std::unique_ptr<TracedValue> frame_node_value(new TracedValue);
-    const StackFrame& frame = frame_node->frame;
-    switch (frame.type) {
-      case StackFrame::Type::TRACE_EVENT_NAME:
-        frame_node_value->SetString(
-            "name", static_cast<const char*>(frame.value));
-        break;
-      case StackFrame::Type::THREAD_NAME:
-        SStringPrintf(&stringify_buffer,
-                      "[Thread: %s]",
-                      static_cast<const char*>(frame.value));
-        frame_node_value->SetString("name", stringify_buffer);
-        break;
-    }
+    frame_node_value->SetString("name", frame_node->frame);
     if (frame_node->parent_frame_index >= 0) {
       SStringPrintf(&stringify_buffer, "%d", frame_node->parent_frame_index);
       frame_node_value->SetString("parent", stringify_buffer);