Only turn on UMA WASM metric when synchronous.

src/compiler/wasm-compiler.h

Index: src/compiler/wasm-compiler.h
diff --git a/src/compiler/wasm-compiler.h b/src/compiler/wasm-compiler.h
index 1561cc29fe80faffe108a53ed384e31127cdb7a7..f2c9a7f6b8af2dc0aa8b6066a8c2a0e9ffcafee5 100644
--- a/src/compiler/wasm-compiler.h
+++ b/src/compiler/wasm-compiler.h
@@ -48,9 +48,10 @@ namespace compiler {
 class WasmCompilationUnit final {
  public:
   WasmCompilationUnit(Isolate* isolate, wasm::ModuleBytesEnv* module_env,
-                      const wasm::WasmFunction* function);
+                      const wasm::WasmFunction* function, bool is_sync = true);
   WasmCompilationUnit(Isolate* isolate, wasm::ModuleEnv* module_env,
-                      wasm::FunctionBody body, wasm::WasmName name, int index);
+                      wasm::FunctionBody body, wasm::WasmName name, int index,
+                      bool is_sync = true);
 
   Zone* graph_zone() { return graph_zone_.get(); }
   int func_index() const { return func_index_; }
@@ -71,6 +72,7 @@ class WasmCompilationUnit final {
   wasm::ModuleEnv* module_env_;
   wasm::FunctionBody func_body_;
   wasm::WasmName func_name_;
+  bool is_sync_;
   // The graph zone is deallocated at the end of ExecuteCompilation.
   std::unique_ptr<Zone> graph_zone_;
   JSGraph* jsgraph_;
@@ -87,6 +89,8 @@ class WasmCompilationUnit final {
       protected_instructions_;  // Instructions that are protected by the signal
                                 // handler.
 
+  void ExecuteCompilationInternal();
+
   DISALLOW_COPY_AND_ASSIGN(WasmCompilationUnit);
 };