[tracing] Add light dumps in the V8 dump provider

gin/v8_isolate_memory_dump_provider.cc

Index: gin/v8_isolate_memory_dump_provider.cc
diff --git a/gin/v8_isolate_memory_dump_provider.cc b/gin/v8_isolate_memory_dump_provider.cc
index 2d261eb9ecc1d26f5cf8d6a88f9dfc238e71a572..ab1b152eaa67ed9a7e184f31668b85b998137a38 100644
--- a/gin/v8_isolate_memory_dump_provider.cc
+++ b/gin/v8_isolate_memory_dump_provider.cc
@@ -35,14 +35,15 @@ bool V8IsolateMemoryDumpProvider::OnMemoryDump(
 
   if (isolate_holder_->access_mode() == IsolateHolder::kUseLocker) {
     v8::Locker locked(isolate_holder_->isolate());
-    DumpHeapStatistics(process_memory_dump);
+    DumpHeapStatistics(args, process_memory_dump);
   } else {
-    DumpHeapStatistics(process_memory_dump);
+    DumpHeapStatistics(args, process_memory_dump);
   }
   return true;
 }
 
 void V8IsolateMemoryDumpProvider::DumpHeapStatistics(
+    const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* process_memory_dump) {
   std::string dump_base_name =
       base::StringPrintf("v8/isolate_%p", isolate_holder_->isolate());
@@ -93,6 +94,11 @@ void V8IsolateMemoryDumpProvider::DumpHeapStatistics(
       base::trace_event::MemoryAllocatorDump::kUnitsBytes,
       heap_statistics.used_heap_size() - known_spaces_used_size);
 
+  // If light dump is requested, then object statistics are not dumped
+  if (args.level_of_detail ==
+      base::trace_event::MemoryDumpArgs::LevelOfDetail::LOW)
+    return;
+
   // Dump statistics of the heap's live objects from last GC.
   std::string object_name_prefix = dump_base_name + "/heap_objects";
   bool did_dump_object_stats = false;