Bug 1391405: Part 1 - Add WebIDL versions of much used Components.utils helpers. r=gabor,qdot

In the code that I'm profiling, the XPC WrappedNative overhead of calling
these functions adds up to about a quarter of the time spent executing the
code. The overhead of the WebIDL versions is negligible.

MozReview-Commit-ID: 30qJy5RtP9d

--HG--
extra : rebase_source : 4fe73f4b9bde052a0eadf7d5634f792e16ca1c94
extra : histedit_source : ec61152a0181f3b0e28023c951e7181c43216d2f

dom/base/ChromeUtils.cpp

@@ -5,6 +5,9 @@
 
 #include "ChromeUtils.h"
 
+#include "jsfriendapi.h"
+#include "WrapperFactory.h"
+
 #include "mozilla/Base64.h"
 #include "mozilla/BasePrincipal.h"
 
@@ -126,6 +129,53 @@ ThreadSafeChromeUtils::Base64URLDecode(GlobalObject& aGlobal,
   aRetval.set(buffer);
 }
 
+/* static */ void
+ChromeUtils::WaiveXrays(GlobalObject& aGlobal,
+                        JS::HandleValue aVal,
+                        JS::MutableHandleValue aRetval,
+                        ErrorResult& aRv)
+{
+  JS::RootedValue value(aGlobal.Context(), aVal);
+  if (!xpc::WrapperFactory::WaiveXrayAndWrap(aGlobal.Context(), &value)) {
+    aRv.NoteJSContextException(aGlobal.Context());
+  } else {
+    aRetval.set(value);
+  }
+}
+
+/* static */ void
+ChromeUtils::UnwaiveXrays(GlobalObject& aGlobal,
+                          JS::HandleValue aVal,
+                          JS::MutableHandleValue aRetval,
+                          ErrorResult& aRv)
+{
+  if (!aVal.isObject()) {
+      aRetval.set(aVal);
+      return;
+  }
+
+  JS::RootedObject obj(aGlobal.Context(), js::UncheckedUnwrap(&aVal.toObject()));
+  if (!JS_WrapObject(aGlobal.Context(), &obj)) {
+    aRv.NoteJSContextException(aGlobal.Context());
+  } else {
+    aRetval.setObject(*obj);
+  }
+}
+
+/* static */ void
+ChromeUtils::GetClassName(GlobalObject& aGlobal,
+                          JS::HandleObject aObj,
+                          bool aUnwrap,
+                          nsAString& aRetval)
+{
+  JS::RootedObject obj(aGlobal.Context(), aObj);
+  if (aUnwrap) {
+    obj = js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
+  }
+
+  aRetval = NS_ConvertUTF8toUTF16(nsDependentCString(js::GetObjectClass(obj)->name));
+}
+
 /* static */ void
 ChromeUtils::OriginAttributesToSuffix(dom::GlobalObject& aGlobal,
                                       const dom::OriginAttributesDictionary& aAttrs,

dom/base/ChromeUtils.h

@@ -124,6 +124,21 @@ public:
                 const nsAString& aUrl,
                 const dom::CompileScriptOptionsDictionary& aOptions,
                 ErrorResult& aRv);
+
+  static void WaiveXrays(GlobalObject& aGlobal,
+                         JS::HandleValue aVal,
+                         JS::MutableHandleValue aRetval,
+                         ErrorResult& aRv);
+
+  static void UnwaiveXrays(GlobalObject& aGlobal,
+                           JS::HandleValue aVal,
+                           JS::MutableHandleValue aRetval,
+                           ErrorResult& aRv);
+
+  static void GetClassName(GlobalObject& aGlobal,
+                           JS::HandleObject aObj,
+                           bool aUnwrap,
+                           nsAString& aRetval);
 };
 
 } // namespace dom

dom/webidl/ChromeUtils.webidl

@@ -69,6 +69,27 @@ interface ChromeUtils : ThreadSafeChromeUtils {
   [NewObject, Throws]
   static Promise<PrecompiledScript>
   compileScript(DOMString url, optional CompileScriptOptionsDictionary options);
+
+  /**
+   * Waive Xray on a given value. Identity op for primitives.
+   */
+  [Throws]
+  static any waiveXrays(any val);
+
+  /**
+   * Strip off Xray waivers on a given value. Identity op for primitives.
+   */
+  [Throws]
+  static any unwaiveXrays(any val);
+
+  /**
+   * Gets the name of the JSClass of the object.
+   *
+   * if |unwrap| is true, all wrappers are unwrapped first. Unless you're
+   * specifically trying to detect whether the object is a proxy, this is
+   * probably what you want.
+   */
+  static DOMString getClassName(object obj, optional boolean unwrap = true);
 };
 
 /**