Bug 1293596 (part 8) - Make nsIWidget::EnableDragDrop() infallible. r=jimm.

Its return value is only checked in one low-value assertion.

The patch also does the following.

- Removes the Android and GTK overloadings of EnableDragDrop(), which are
  identical to the nsBaseWidget one.

- Streamlines the Windows implementation: fixes the indentation and takes
  advantage of infallible |new|.

--HG--
extra : rebase_source : d090848cf5ea2e92c0188b07559c1e1f3899829f

dom/plugins/base/nsPluginInstanceOwner.cpp

@@ -3394,7 +3394,6 @@ NS_IMETHODIMP nsPluginInstanceOwner::CreateWidget(void)
       }
     }
 
-
     mWidget->EnableDragDrop(true);
     mWidget->Show(false);
     mWidget->Enable(false);

dom/plugins/ipc/PluginWidgetParent.cpp

@@ -126,14 +126,12 @@ PluginWidgetParent::RecvCreate(nsresult* aResult)
     return false;
   }
 
-  DebugOnly<nsresult> drv;
-  drv = mWidget->EnableDragDrop(true);
-  NS_ASSERTION(NS_SUCCEEDED(drv), "widget call failure");
+  mWidget->EnableDragDrop(true);
 
 #if defined(MOZ_WIDGET_GTK)
   // For setup, initially GTK code expects 'window' to hold the parent.
   mWrapper->window = mWidget->GetNativeData(NS_NATIVE_PLUGIN_PORT);
-  drv = mWrapper->CreateXEmbedWindow(false);
+  DebugOnly<nsresult> drv = mWrapper->CreateXEmbedWindow(false);
   NS_ASSERTION(NS_SUCCEEDED(drv), "widget call failure");
   mWrapper->SetAllocation();
   PWLOG("Plugin XID=%p\n", (void*)mWrapper->window);

widget/android/nsWindow.h

@@ -187,7 +187,6 @@ public:
     void SetNativeData(uint32_t aDataType, uintptr_t aVal) override;
     NS_IMETHOD SetTitle(const nsAString& aTitle) override { return NS_OK; }
     NS_IMETHOD SetIcon(const nsAString& aIconSpec) override { return NS_OK; }
-    NS_IMETHOD EnableDragDrop(bool aEnable) override { return NS_OK; }
     NS_IMETHOD CaptureMouse(bool aCapture) override { return NS_ERROR_NOT_IMPLEMENTED; }
     NS_IMETHOD CaptureRollupEvents(nsIRollupListener *aListener,
                                    bool aDoCapture) override { return NS_ERROR_NOT_IMPLEMENTED; }

widget/gtk/nsWindow.cpp

@@ -1879,12 +1879,6 @@ nsWindow::WidgetToScreenOffset()
     return GdkPointToDevicePixels({ x, y });
 }
 
-NS_IMETHODIMP
-nsWindow::EnableDragDrop(bool aEnable)
-{
-    return NS_OK;
-}
-
 NS_IMETHODIMP
 nsWindow::CaptureMouse(bool aCapture)
 {

widget/gtk/nsWindow.h

@@ -148,7 +148,6 @@ public:
     NS_IMETHOD         SetIcon(const nsAString& aIconSpec) override;
     NS_IMETHOD         SetWindowClass(const nsAString& xulWinType) override;
     virtual LayoutDeviceIntPoint WidgetToScreenOffset() override;
-    NS_IMETHOD         EnableDragDrop(bool aEnable) override;
     NS_IMETHOD         CaptureMouse(bool aCapture) override;
     NS_IMETHOD         CaptureRollupEvents(nsIRollupListener *aListener,
                                            bool aDoCapture) override;

widget/nsBaseWidget.cpp

@@ -1599,11 +1599,6 @@ nsBaseWidget::SetNonClientMargins(LayoutDeviceIntMargin &margins)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-NS_IMETHODIMP nsBaseWidget::EnableDragDrop(bool aEnable)
-{
-  return NS_OK;
-}
-
 uint32_t nsBaseWidget::GetMaxTouchPoints() const
 {
   return 0;

widget/nsBaseWidget.h

@@ -223,7 +223,7 @@ public:
   virtual MOZ_MUST_USE nsresult GetRestoredBounds(LayoutDeviceIntRect& aRect) override;
   NS_IMETHOD              SetNonClientMargins(LayoutDeviceIntMargin& aMargins) override;
   virtual LayoutDeviceIntPoint GetClientOffset() override;
-  NS_IMETHOD              EnableDragDrop(bool aEnable) override;
+  virtual void            EnableDragDrop(bool aEnable) override {};
   NS_IMETHOD              GetAttention(int32_t aCycleCount) override;
   virtual bool            HasPendingInputEvent() override;
   NS_IMETHOD              SetIcon(const nsAString &anIconSpec) override;

widget/nsIWidget.h

@@ -1374,10 +1374,9 @@ class nsIWidget : public nsISupports
     virtual bool AsyncPanZoomEnabled() const = 0;
 
     /**
-     * Enables the dropping of files to a widget (XXX this is temporary)
-     *
+     * Enables the dropping of files to a widget.
      */
-    NS_IMETHOD EnableDragDrop(bool aEnable) = 0;
+    virtual void EnableDragDrop(bool aEnable) = 0;
 
     /**
      * Enables/Disables system mouse capture.

widget/windows/nsWindow.cpp

@@ -3507,34 +3507,29 @@ nsWindow::ClientToWindowSize(const LayoutDeviceIntSize& aClientSize)
  *
  **************************************************************/
 
-NS_IMETHODIMP nsWindow::EnableDragDrop(bool aEnable)
+void
+nsWindow::EnableDragDrop(bool aEnable)
 {
   NS_ASSERTION(mWnd, "nsWindow::EnableDragDrop() called after Destroy()");
 
   nsresult rv = NS_ERROR_FAILURE;
   if (aEnable) {
-    if (nullptr == mNativeDragTarget) {
-       mNativeDragTarget = new nsNativeDragTarget(this);
-       if (nullptr != mNativeDragTarget) {
-         mNativeDragTarget->AddRef();
-         if (S_OK == ::CoLockObjectExternal((LPUNKNOWN)mNativeDragTarget,TRUE,FALSE)) {
-           if (S_OK == ::RegisterDragDrop(mWnd, (LPDROPTARGET)mNativeDragTarget)) {
-             rv = NS_OK;
-           }
-         }
-       }
+    if (!mNativeDragTarget) {
+      mNativeDragTarget = new nsNativeDragTarget(this);
+      mNativeDragTarget->AddRef();
+      if (SUCCEEDED(::CoLockObjectExternal((LPUNKNOWN)mNativeDragTarget,
+                                           TRUE, FALSE))) {
+        ::RegisterDragDrop(mWnd, (LPDROPTARGET)mNativeDragTarget);
+      }
     }
   } else {
-    if (nullptr != mWnd && nullptr != mNativeDragTarget) {
+    if (mWnd && mNativeDragTarget) {
       ::RevokeDragDrop(mWnd);
-      if (S_OK == ::CoLockObjectExternal((LPUNKNOWN)mNativeDragTarget, FALSE, TRUE)) {
-        rv = NS_OK;
-      }
+      ::CoLockObjectExternal((LPUNKNOWN)mNativeDragTarget, FALSE, TRUE);
       mNativeDragTarget->DragCancel();
       NS_RELEASE(mNativeDragTarget);
     }
   }
-  return rv;
 }
 
 /**************************************************************

widget/windows/nsWindow.h

@@ -165,7 +165,7 @@ public:
   virtual LayoutDeviceIntSize ClientToWindowSize(const LayoutDeviceIntSize& aClientSize) override;
   NS_IMETHOD              DispatchEvent(mozilla::WidgetGUIEvent* aEvent,
                                         nsEventStatus& aStatus) override;
-  NS_IMETHOD              EnableDragDrop(bool aEnable) override;
+  virtual void            EnableDragDrop(bool aEnable) override;
   NS_IMETHOD              CaptureMouse(bool aCapture) override;
   NS_IMETHOD              CaptureRollupEvents(nsIRollupListener * aListener,
                                               bool aDoCapture) override;