fix: multiple dock icons when calling dock.show/hide

shell/browser/browser.h

@@ -355,6 +355,7 @@ class Browser : public WindowListObserver {
 
 #if defined(OS_MAC)
   std::unique_ptr<ui::ScopedPasswordInputEnabler> password_input_enabler_;
+  base::Time last_dock_show_;
 #endif
 
 #if defined(OS_LINUX) || defined(OS_WIN)

shell/browser/browser_mac.mm

@@ -383,6 +383,20 @@ void RemoveFromLoginItems() {
 }
 
 void Browser::DockHide() {
+  // Transforming application state from UIElement to Foreground is an
+  // asyncronous operation, and unfortunately there is currently no way to know
+  // when it is finished.
+  // So if we call DockHide => DockShow => DockHide => DockShow in a very short
+  // time, we would triger a bug of macOS that, there would be multiple dock
+  // icons of the app left in system.
+  // To work around this, we make sure DockHide does nothing if it is called
+  // immediately after DockShow. After some experiments, 1 second seems to be
+  // a proper interval.
+  if (!last_dock_show_.is_null() &&
+      base::Time::Now() - last_dock_show_ < base::TimeDelta::FromSeconds(1)) {
+    return;
+  }
+
   for (auto* const& window : WindowList::GetWindows())
     [window->GetNativeWindow().GetNativeNSWindow() setCanHide:NO];
 
@@ -398,6 +412,7 @@ void RemoveFromLoginItems() {
 }
 
 v8::Local<v8::Promise> Browser::DockShow(v8::Isolate* isolate) {
+  last_dock_show_ = base::Time::Now();
   gin_helper::Promise<void> promise(isolate);
   v8::Local<v8::Promise> handle = promise.GetHandle();
 

spec-main/api-app-spec.ts

@@ -1437,6 +1437,16 @@ describe('app module', () => {
       });
     });
 
+    describe('dock.hide', () => {
+      it('should not throw', () => {
+        app.dock.hide();
+        expect(app.dock.isVisible()).to.equal(false);
+      });
+    });
+
+    // Note that dock.show tests should run after dock.hide tests, to work
+    // around a bug of macOS.
+    // See https://github.com/electron/electron/pull/25269 for more.
     describe('dock.show', () => {
       it('should not throw', () => {
         return app.dock.show().then(() => {
@@ -1452,13 +1462,6 @@ describe('app module', () => {
         await expect(app.dock.show()).to.eventually.be.fulfilled.equal(undefined);
       });
     });
-
-    describe('dock.hide', () => {
-      it('should not throw', () => {
-        app.dock.hide();
-        expect(app.dock.isVisible()).to.equal(false);
-      });
-    });
   });
 
   describe('whenReady', () => {