Add 'activate-with-no-open-windows' event for app.

Fixes #194.

browser/api/atom_api_app.cc

@@ -44,6 +44,10 @@ void App::OnOpenURL(const std::string& url) {
   Emit("open-url", &args);
 }
 
+void App::OnActivateWithNoOpenWindows() {
+  Emit("activate-with-no-open-windows");
+}
+
 void App::OnWillFinishLaunching() {
   Emit("will-finish-launching");
 }

browser/api/atom_api_app.h

@@ -29,6 +29,7 @@ class App : public EventEmitter,
   virtual void OnOpenFile(bool* prevent_default,
                           const std::string& file_path) OVERRIDE;
   virtual void OnOpenURL(const std::string& url) OVERRIDE;
+  virtual void OnActivateWithNoOpenWindows() OVERRIDE;
   virtual void OnWillFinishLaunching() OVERRIDE;
   virtual void OnFinishLaunching() OVERRIDE;
 

browser/atom_application_delegate_mac.mm

@@ -35,4 +35,15 @@
   }
 }
 
+- (BOOL)applicationShouldHandleReopen:(NSApplication*)theApplication
+                    hasVisibleWindows:(BOOL)flag {
+  atom::Browser* browser = atom::Browser::Get();
+  if (flag) {
+    return YES;
+  } else {
+    browser->ActivateWithNoOpenWindows();
+    return NO;
+  }
+}
+
 @end

browser/browser.cc

@@ -74,6 +74,10 @@ void Browser::OpenURL(const std::string& url) {
   FOR_EACH_OBSERVER(BrowserObserver, observers_, OnOpenURL(url));
 }
 
+void Browser::ActivateWithNoOpenWindows() {
+  FOR_EACH_OBSERVER(BrowserObserver, observers_, OnActivateWithNoOpenWindows());
+}
+
 void Browser::WillFinishLaunching() {
   FOR_EACH_OBSERVER(BrowserObserver, observers_, OnWillFinishLaunching());
 }

browser/browser.h

@@ -62,6 +62,9 @@ class Browser : public WindowListObserver {
   // Tell the application to open a url.
   void OpenURL(const std::string& url);
 
+  // Tell the application that application is activated with no open windows.
+  void ActivateWithNoOpenWindows();
+
   // Tell the application the loading has been done.
   void WillFinishLaunching();
   void DidFinishLaunching();

browser/browser_observer.h

@@ -26,6 +26,10 @@ class BrowserObserver {
   // Browser is used to open a url.
   virtual void OnOpenURL(const std::string& url) {}
 
+  // The browser is activated with no open windows (usually by clicking on the
+  // dock icon).
+  virtual void OnActivateWithNoOpenWindows() {}
+
   // The browser has finished loading.
   virtual void OnWillFinishLaunching() {}
   virtual void OnFinishLaunching() {}

docs/api/browser/app.md

@@ -66,6 +66,12 @@ must be registered to be opened by your application.
 
 You should call `event.preventDefault()` if you want to handle this event.
 
+## Event: activate-with-no-open-windows
+
+Emitted when the application is activated while there is no opened windows. It
+usually happens when user has closed all of application's windows and then
+click on the application's dock icon.
+
 ## app.quit()
 
 Try to close all windows. If all windows are successfully closed, the