Cleanup code of beginFrameSubscription

atom/browser/api/atom_api_web_contents.cc

@@ -1181,15 +1181,14 @@ void WebContents::SendInputEvent(v8::Isolate* isolate,
       isolate, "Invalid event object")));
 }
 
-void WebContents::BeginFrameSubscription(
-  mate::Arguments* args) {
-  FrameSubscriber::FrameCaptureCallback callback;
+void WebContents::BeginFrameSubscription(mate::Arguments* args) {
   bool only_dirty = false;
+  FrameSubscriber::FrameCaptureCallback callback;
 
-  if (!args->GetNext(&callback)) {
   args->GetNext(&only_dirty);
-    if (!args->GetNext(&callback))
-      args->ThrowTypeError("'callback' must be defined");
+  if (!args->GetNext(&callback)) {
+    args->ThrowError();
+    return;
   }
 
   const auto view = web_contents()->GetRenderWidgetHostView();

atom/browser/api/frame_subscriber.cc

@@ -5,8 +5,8 @@
 #include "atom/browser/api/frame_subscriber.h"
 
 #include "base/bind.h"
-#include "atom/common/node_includes.h"
 #include "atom/common/native_mate_converters/gfx_converter.h"
+#include "atom/common/node_includes.h"
 #include "content/public/browser/render_widget_host.h"
 
 namespace atom {
@@ -17,8 +17,11 @@ FrameSubscriber::FrameSubscriber(v8::Isolate* isolate,
                                  content::RenderWidgetHostView* view,
                                  const FrameCaptureCallback& callback,
                                  bool only_dirty)
-    : isolate_(isolate), view_(view), callback_(callback),
-      only_dirty_(only_dirty), weak_factory_(this) {
+    : isolate_(isolate),
+      view_(view),
+      callback_(callback),
+      only_dirty_(only_dirty),
+      weak_factory_(this) {
 }
 
 bool FrameSubscriber::ShouldCaptureFrame(
@@ -48,7 +51,8 @@ bool FrameSubscriber::ShouldCaptureFrame(
 }
 
 void FrameSubscriber::OnFrameDelivered(const FrameCaptureCallback& callback,
-  const gfx::Rect& damage_rect, const SkBitmap& bitmap,
+                                       const gfx::Rect& damage_rect,
+                                       const SkBitmap& bitmap,
                                        content::ReadbackResponse response) {
   if (response != content::ReadbackResponse::READBACK_SUCCESS)
     return;

atom/browser/api/frame_subscriber.h

@@ -35,7 +35,8 @@ class FrameSubscriber : public content::RenderWidgetHostViewFrameSubscriber {
 
  private:
   void OnFrameDelivered(const FrameCaptureCallback& callback,
-    const gfx::Rect& damage_rect, const SkBitmap& bitmap,
+                        const gfx::Rect& damage_rect,
+                        const SkBitmap& bitmap,
                         content::ReadbackResponse response);
 
   v8::Isolate* isolate_;

docs/api/web-contents.md

@@ -921,7 +921,7 @@ For the `mouseWheel` event, the `event` object also have following properties:
 
 ### `webContents.beginFrameSubscription([onlyDirty ,]callback)`
 
-* `onlyDirty` Boolean
+* `onlyDirty` Boolean (optional) - Defaults to `false`
 * `callback` Function
 
 Begin subscribing for presentation events and captured frames, the `callback`