Bug 1353939 - Disable drag service in headless mode. r=jrmuizel

Drag service calls into GTK causing a crash in headless mode.

widget/gtk/nsDragService.cpp

@@ -26,6 +26,7 @@
 #include "nsCRT.h"
 #include "mozilla/BasicEvents.h"
 #include "mozilla/Services.h"
+#include "mozilla/ClearOnShutdown.h"
 
 #include "gfxXlibSurface.h"
 #include "gfxContext.h"
@@ -151,13 +152,20 @@ nsDragService::~nsDragService()
 
 NS_IMPL_ISUPPORTS_INHERITED(nsDragService, nsBaseDragService, nsIObserver)
 
-/* static */ nsDragService*
+mozilla::StaticRefPtr<nsDragService> sDragServiceInstance;
+/* static */ already_AddRefed<nsDragService>
 nsDragService::GetInstance()
 {
-    static const nsIID iid = NS_DRAGSERVICE_CID;
-    nsCOMPtr<nsIDragService> dragService = do_GetService(iid);
-    return static_cast<nsDragService*>(dragService.get());
-    // We rely on XPCOM keeping a reference to the service.
+  if (gfxPlatform::IsHeadless()) {
+    return nullptr;
+  }
+  if (!sDragServiceInstance) {
+    sDragServiceInstance = new nsDragService();
+    ClearOnShutdown(&sDragServiceInstance);
+  }
+
+  RefPtr<nsDragService> service = sDragServiceInstance.get();
+  return service.forget();
 }
 
 // nsIObserver

widget/gtk/nsDragService.h

@@ -85,7 +85,7 @@ public:
     // Methods called from nsWindow to handle responding to GTK drag
     // destination signals
 
-    static nsDragService* GetInstance();
+    static already_AddRefed<nsDragService> GetInstance();
 
     void TargetDataReceived          (GtkWidget         *aWidget,
                                       GdkDragContext    *aContext,

widget/gtk/nsWidgetFactory.cpp

@@ -74,7 +74,7 @@ NS_GENERIC_FACTORY_CONSTRUCTOR(nsHTMLFormatConverter)
 NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(nsIdleServiceGTK, nsIdleServiceGTK::GetInstance)
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsClipboardHelper)
 NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsClipboard, Init)
-NS_GENERIC_FACTORY_CONSTRUCTOR(nsDragService)
+NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(nsDragService, nsDragService::GetInstance)
 #endif
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsSound)
 NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(ScreenManager, ScreenManager::GetAddRefedSingleton)

widget/gtk/nsWindow.cpp

@@ -735,7 +735,7 @@ nsWindow::Destroy()
     }
 
     // dragService will be null after shutdown of the service manager.
-    nsDragService *dragService = nsDragService::GetInstance();
+    RefPtr<nsDragService> dragService = nsDragService::GetInstance();
     if (dragService && this == dragService->GetMostRecentDestWindow()) {
         dragService->ScheduleLeaveEvent();
     }
@@ -3397,7 +3397,8 @@ nsWindow::OnDragDataReceivedEvent(GtkWidget *aWidget,
 {
     LOGDRAG(("nsWindow::OnDragDataReceived(%p)\n", (void*)this));
 
-    nsDragService::GetInstance()->
+    RefPtr<nsDragService> dragService = nsDragService::GetInstance();
+    dragService->
         TargetDataReceived(aWidget, aDragContext, aX, aY,
                            aSelectionData, aInfo, aTime);
 }
@@ -5911,7 +5912,8 @@ drag_motion_event_cb(GtkWidget *aWidget,
 
     LayoutDeviceIntPoint point = window->GdkPointToDevicePixels({ retx, rety });
 
-    return nsDragService::GetInstance()->
+    RefPtr<nsDragService> dragService = nsDragService::GetInstance();
+    return dragService->
         ScheduleMotionEvent(innerMostWindow, aDragContext,
                             point, aTime);
 }
@@ -5926,7 +5928,7 @@ drag_leave_event_cb(GtkWidget *aWidget,
     if (!window)
         return;
 
-    nsDragService *dragService = nsDragService::GetInstance();
+    RefPtr<nsDragService> dragService = nsDragService::GetInstance();
 
     nsWindow *mostRecentDragWindow = dragService->GetMostRecentDestWindow();
     if (!mostRecentDragWindow) {
@@ -5983,7 +5985,8 @@ drag_drop_event_cb(GtkWidget *aWidget,
 
     LayoutDeviceIntPoint point = window->GdkPointToDevicePixels({ retx, rety });
 
-    return nsDragService::GetInstance()->
+    RefPtr<nsDragService> dragService = nsDragService::GetInstance();
+    return dragService->
         ScheduleDropEvent(innerMostWindow, aDragContext,
                           point, aTime);
 }

widget/headless/HeadlessWidget.cpp

@@ -126,6 +126,8 @@ HeadlessWidget::DispatchEvent(WidgetGUIEvent* aEvent, nsEventStatus& aStatus)
 
   if (mAttachedWidgetListener) {
     aStatus = mAttachedWidgetListener->HandleEvent(aEvent, mUseAttachedEvents);
+  } else if (mWidgetListener) {
+    aStatus = mWidgetListener->HandleEvent(aEvent, mUseAttachedEvents);
   }
 
   return NS_OK;

widget/headless/tests/headless_button.html

@@ -0,0 +1,6 @@
+<html>
+<head><meta content="text/html; charset=utf-8" http-equiv="Content-Type"></head>
+<body>
+<button id="btn">button</button>
+</body>
+</html>

widget/headless/tests/test_headless.js

@@ -12,6 +12,8 @@ server.start(-1);
 const ROOT = `http://localhost:${server.identity.primaryPort}`;
 const BASE = `${ROOT}/`;
 const HEADLESS_URL = `${BASE}/headless.html`;
+const HEADLESS_BUTTON_URL = `${BASE}/headless_button.html`;
+do_register_cleanup(() => { server.stop(() => {})});
 
 function loadContentWindow(webNavigation, uri) {
   return new Promise((resolve, reject) => {
@@ -88,7 +90,52 @@ add_task(function* test_snapshot() {
   ok(found, "Found blue text on page.");
 
   webNavigation.close();
-  yield new Promise((resolve) => {
-    server.stop(resolve);
-  });
+});
+
+// Ensure keydown events are triggered on the windowless browser.
+add_task(function* test_keydown() {
+  let windowlessBrowser = Services.appShell.createWindowlessBrowser(false);
+  let webNavigation = windowlessBrowser.QueryInterface(Ci.nsIWebNavigation);
+  let contentWindow = yield loadContentWindow(webNavigation, HEADLESS_URL);
+
+  let utils = contentWindow.QueryInterface(Ci.nsIInterfaceRequestor)
+                           .getInterface(Ci.nsIDOMWindowUtils);
+  let keydown = new Promise((resolve) => {
+    contentWindow.addEventListener("keydown", () => {
+      resolve();
+    }, { once: true });
+  })
+  utils.sendKeyEvent("keydown", 65, 65, 0);
+
+  yield keydown;
+  ok(true, "Send keydown didn't crash");
+
+  webNavigation.close();
+});
+
+// Test dragging the mouse on a button to ensure the creation of the drag
+// service doesn't crash in headless.
+add_task(function* test_mouse_drag() {
+  let windowlessBrowser = Services.appShell.createWindowlessBrowser(false);
+  let webNavigation = windowlessBrowser.QueryInterface(Ci.nsIWebNavigation);
+  let contentWindow = yield loadContentWindow(webNavigation, HEADLESS_BUTTON_URL);
+  contentWindow.resizeTo(400, 400);
+
+  let target = contentWindow.document.getElementById('btn');
+  let rect = target.getBoundingClientRect();
+  let left = rect.left;
+  let top = rect.top;
+
+  let utils = contentWindow.QueryInterface(Ci.nsIInterfaceRequestor)
+                           .getInterface(Ci.nsIDOMWindowUtils);
+  utils.sendMouseEvent("mousedown", left, top, 0, 1, 0, false, 0, 0);
+  utils.sendMouseEvent("mousemove", left, top, 0, 1, 0, false, 0, 0);
+  // Wait for a turn of the event loop since the synthetic mouse event
+  // that creates the drag service is processed during the refresh driver.
+  yield new Promise((r) => {do_execute_soon(r)});
+  utils.sendMouseEvent("mouseup", left, top, 0, 1, 0, false, 0, 0);
+
+  ok(true, "Send mouse event didn't crash");
+
+  webNavigation.close();
 });

widget/headless/tests/xpcshell.ini

@@ -1,4 +1,6 @@
 [test_headless.js]
 skip-if = os != "linux"
 headless = true
-support-files = headless.html
+support-files =
+  headless.html
+  headless_button.html