Fix use of history timers in background threads.

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 aab4e1bdcddbd386f9c422223a64fa3aa8cac398..32d52e559bca7cc6469eae8725bea9137e3c4c83 100644
--- a/src/compiler/wasm-compiler.h
+++ b/src/compiler/wasm-compiler.h
@@ -89,8 +89,6 @@ class WasmCompilationUnit final {
       protected_instructions_;  // Instructions that are protected by the signal
                                 // handler.
 
-  void ExecuteCompilationInternal();
-
   DISALLOW_COPY_AND_ASSIGN(WasmCompilationUnit);
 };