Fix use of history timers in background threads.

src/wasm/module-compiler.h

Index: src/wasm/module-compiler.h
diff --git a/src/wasm/module-compiler.h b/src/wasm/module-compiler.h
index cac664924eb141e1fc8019d6bd920bb6b9afc0f3..daa82bc5a39b69701074235f76380d922f5a544c 100644
--- a/src/wasm/module-compiler.h
+++ b/src/wasm/module-compiler.h
@@ -69,8 +69,7 @@ class ModuleCompiler {
 
   Isolate* isolate_;
   std::unique_ptr<WasmModule> module_;
-  std::shared_ptr<Counters> counters_shared_;
-  Counters* counters_;
+  const std::shared_ptr<Counters> async_counters_;
   bool is_sync_;
   std::vector<std::unique_ptr<compiler::WasmCompilationUnit>>
       compilation_units_;
@@ -82,6 +81,8 @@ class ModuleCompiler {
   bool finisher_is_running_ = false;
   CancelableTaskManager background_task_manager_;
 
+  Counters* counters() const { return async_counters_.get(); }
+
   // Run by each compilation task and by the main thread. The
   // no_finisher_callback is called within the result_mutex_ lock when no
   // finishing task is running, i.e. when the finisher_is_running_ flag is not
@@ -178,8 +179,7 @@ class InstanceBuilder {
 
   Isolate* isolate_;
   WasmModule* const module_;
-  std::shared_ptr<Counters> counters_shared_;
-  Counters* counters_;
+  const std::shared_ptr<Counters> async_counters_;
   ErrorThrower* thrower_;
   Handle<WasmModuleObject> module_object_;
   Handle<JSReceiver> ffi_;        // TODO(titzer): Use MaybeHandle
@@ -191,6 +191,8 @@ class InstanceBuilder {
   JSToWasmWrapperCache js_to_wasm_cache_;
   WeakCallbackInfo<void>::Callback instance_finalizer_callback_;
 
+  Counters* counters() const { return async_counters_.get(); }
+
 // Helper routines to print out errors with imports.
 #define ERROR_THROWER_WITH_MESSAGE(TYPE)                                      \
   void Report##TYPE(const char* error, uint32_t index,                        \
@@ -296,8 +298,7 @@ class AsyncCompileJob {
   class FinishModule;
 
   Isolate* isolate_;
-  std::shared_ptr<Counters> counters_shared_;
-  Counters* counters_;
+  const std::shared_ptr<Counters> async_counters_;
   std::unique_ptr<byte[]> bytes_copy_;
   ModuleWireBytes wire_bytes_;
   Handle<Context> context_;
@@ -320,6 +321,8 @@ class AsyncCompileJob {
   int32_t num_pending_foreground_tasks_ = 0;
 #endif
 
+  Counters* counters() const { return async_counters_.get(); }
+
   void ReopenHandlesInDeferredScope();
 
   void AsyncCompileFailed(ErrorThrower& thrower);