Add "will-navigate" event for BrowserWindow

atom/browser/api/atom_api_window.cc

@@ -92,6 +92,12 @@ void Window::WillCreatePopupWindow(const base::string16& frame_name,
   Emit("-new-window", args);
 }
 
+void Window::WillNavigate(bool* prevent_default, const GURL& url) {
+  base::ListValue args;
+  args.AppendString(url.spec());
+  *prevent_default = Emit("will-navigate", args);
+}
+
 void Window::WillCloseWindow(bool* prevent_default) {
   *prevent_default = Emit("close");
 }

atom/browser/api/atom_api_window.h

@@ -50,6 +50,7 @@ class Window : public mate::EventEmitter,
                              const GURL& target_url,
                              const std::string& partition_id,
                              WindowOpenDisposition disposition) override;
+  void WillNavigate(bool* prevent_default, const GURL& url) override;
   void WillCloseWindow(bool* prevent_default) override;
   void OnWindowClosed() override;
   void OnWindowBlur() override;

atom/browser/native_window.cc

@@ -169,7 +169,7 @@ NativeWindow* NativeWindow::FromRenderView(int process_id, int routing_id) {
       return window;
   }
 
-  return NULL;
+  return nullptr;
 }
 
 void NativeWindow::InitFromOptions(const mate::Dictionary& options) {
@@ -370,13 +370,13 @@ void NativeWindow::CloseWebContents() {
 
 content::WebContents* NativeWindow::GetWebContents() const {
   if (!inspectable_web_contents_)
-    return NULL;
+    return nullptr;
   return inspectable_web_contents()->GetWebContents();
 }
 
 content::WebContents* NativeWindow::GetDevToolsWebContents() const {
   if (!inspectable_web_contents_)
-    return NULL;
+    return nullptr;
   return inspectable_web_contents()->devtools_web_contents();
 }
 
@@ -524,9 +524,17 @@ content::WebContents* NativeWindow::OpenURLFromTab(
                                             params.url,
                                             "",
                                             params.disposition));
-    return NULL;
+    return nullptr;
   }
 
+  // Give user a chance to prevent navigation.
+  bool prevent_default = false;
+  FOR_EACH_OBSERVER(NativeWindowObserver,
+                    observers_,
+                    WillNavigate(&prevent_default, params.url));
+  if (prevent_default)
+    return nullptr;
+
   content::NavigationController::LoadURLParams load_url_params(params.url);
   load_url_params.referrer = params.referrer;
   load_url_params.transition_type = params.transition;

atom/browser/native_window_observer.h

@@ -27,6 +27,9 @@ class NativeWindowObserver {
                                      const std::string& partition_id,
                                      WindowOpenDisposition disposition) {}
 
+  // Called when user is starting an navigation in web page.
+  virtual void WillNavigate(bool* prevent_default, const GURL& url) {}
+
   // Called when the window is gonna closed.
   virtual void WillCloseWindow(bool* prevent_default) {}