Bug 1733465 part 2: Modernize nsViewManager::GetRootWidget() to use already_AddRefed return value, instead of requiring getter_AddRefs at callsite. r=tnikkel

This patch shouldn't change behavior at all.

This patch replaces a manual NS_ADDREF call with typesafe code that manages the
reference count for us.  This reduces repeated boilerplate code, in the
implementation as well as the callsites.

Differential Revision: https://phabricator.services.mozilla.com/D127179

accessible/android/SessionAccessibility.cpp

@@ -182,8 +182,7 @@ RefPtr<SessionAccessibility> SessionAccessibility::GetInstanceFor(
     return nullptr;
   }
 
-  nsCOMPtr<nsIWidget> rootWidget;
-  vm->GetRootWidget(getter_AddRefs(rootWidget));
+  nsCOMPtr<nsIWidget> rootWidget = vm->GetRootWidget();
   // `rootWidget` can be one of several types. Here we make sure it is an
   // android nsWindow.
   if (RefPtr<nsWindow> window = nsWindow::From(rootWidget)) {

accessible/generic/DocAccessible.cpp

@@ -932,8 +932,7 @@ void* DocAccessible::GetNativeWindow() const {
   nsViewManager* vm = mPresShell->GetViewManager();
   if (!vm) return nullptr;
 
-  nsCOMPtr<nsIWidget> widget;
-  vm->GetRootWidget(getter_AddRefs(widget));
+  nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
   if (widget) return widget->GetNativeData(NS_NATIVE_WINDOW);
 
   return nullptr;

accessible/windows/msaa/MsaaAccessible.cpp

@@ -251,8 +251,7 @@ HWND MsaaAccessible::GetHWNDFor(Accessible* aAccessible) {
     nsIWidget* widget = frame->GetNearestWidget();
     if (widget && widget->IsVisible()) {
       if (nsViewManager* vm = document->PresShellPtr()->GetViewManager()) {
-        nsCOMPtr<nsIWidget> rootWidget;
-        vm->GetRootWidget(getter_AddRefs(rootWidget));
+        nsCOMPtr<nsIWidget> rootWidget = vm->GetRootWidget();
         // Make sure the accessible belongs to popup. If not then use
         // document HWND (which might be different from root widget in the
         // case of window emulation).

dom/base/nsContentSink.cpp

@@ -1032,8 +1032,7 @@ nsresult nsContentSink::DidProcessATokenImpl() {
       (mDeflectedCount % StaticPrefs::content_sink_event_probe_rate()) == 0) {
     nsViewManager* vm = presShell->GetViewManager();
     NS_ENSURE_TRUE(vm, NS_ERROR_FAILURE);
-    nsCOMPtr<nsIWidget> widget;
-    vm->GetRootWidget(getter_AddRefs(widget));
+    nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
     mHasPendingEvent = widget && widget->HasPendingInputEvent();
   }
 

dom/base/nsFocusManager.cpp

@@ -1370,8 +1370,7 @@ void nsFocusManager::EnsureCurrentWidgetFocused(CallerType aCallerType) {
   if (!vm) {
     return;
   }
-  nsCOMPtr<nsIWidget> widget;
-  vm->GetRootWidget(getter_AddRefs(widget));
+  nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
   if (!widget) {
     return;
   }
@@ -2581,8 +2580,7 @@ void nsFocusManager::Focus(
 
   if (aAdjustWidget && !sTestMode) {
     if (nsViewManager* vm = presShell->GetViewManager()) {
-      nsCOMPtr<nsIWidget> widget;
-      vm->GetRootWidget(getter_AddRefs(widget));
+      nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
       if (widget)
         widget->SetFocus(nsIWidget::Raise::No, aFlags & FLAG_NONSYSTEMCALLER
                                                    ? CallerType::NonSystem
@@ -2966,8 +2964,7 @@ void nsFocusManager::RaiseWindow(nsPIDOMWindowOuter* aWindow,
   }
 
   if (nsViewManager* vm = presShell->GetViewManager()) {
-    nsCOMPtr<nsIWidget> widget;
-    vm->GetRootWidget(getter_AddRefs(widget));
+    nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
     if (widget) {
       widget->SetFocus(nsIWidget::Raise::Yes, aCallerType);
     }

dom/ipc/BrowserParent.cpp

@@ -349,10 +349,7 @@ already_AddRefed<nsPIDOMWindowOuter> BrowserParent::GetParentWindowOuter() {
 already_AddRefed<nsIWidget> BrowserParent::GetTopLevelWidget() {
   if (RefPtr<Element> element = mFrameElement) {
     if (PresShell* presShell = element->OwnerDoc()->GetPresShell()) {
-      nsViewManager* vm = presShell->GetViewManager();
-      nsCOMPtr<nsIWidget> widget;
-      vm->GetRootWidget(getter_AddRefs(widget));
-      return widget.forget();
+      return presShell->GetViewManager()->GetRootWidget();
     }
   }
   return nullptr;

layout/base/PresShell.cpp

@@ -8837,9 +8837,8 @@ bool PresShell::EventHandler::AdjustContextMenuKeyEvent(
   nsRootPresContext* rootPC = GetPresContext()->GetRootPresContext();
   aMouseEvent->mRefPoint = LayoutDeviceIntPoint(0, 0);
   if (rootPC) {
-    rootPC->PresShell()->GetViewManager()->GetRootWidget(
-        getter_AddRefs(aMouseEvent->mWidget));
-
+    aMouseEvent->mWidget =
+        rootPC->PresShell()->GetViewManager()->GetRootWidget();
     if (aMouseEvent->mWidget) {
       // default the refpoint to the topleft of our document
       nsPoint offset(0, 0);

layout/base/nsPresContext.cpp

@@ -1081,8 +1081,14 @@ nsIWidget* nsPresContext::GetRootWidget() const {
   if (!vm) {
     return nullptr;
   }
-  nsCOMPtr<nsIWidget> widget;
-  vm->GetRootWidget(getter_AddRefs(widget));
+
+  // XXXdholbert REVIEW NOTE: It's kind of sketchy that we're returning a raw
+  // pointer to a refcounted object here, when we've got an owning reference
+  // which we release just as we return the raw pointer.  Plus, it's wasteful
+  // to be incurring an AddRef/Release operation before the object actually
+  // even gets used (and potentially AddRef'ed again) by the caller.  I'll be
+  // cleaning this up to address these issues in the next patch in this series.
+  nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
   return widget.get();
 }
 

layout/generic/nsIFrame.cpp

@@ -2337,8 +2337,8 @@ already_AddRefed<ComputedStyle> nsIFrame::ComputeSelectionStyle(
 template <typename SizeOrMaxSize>
 static inline bool IsIntrinsicKeyword(const SizeOrMaxSize& aSize) {
   // All keywords other than auto/none/-moz-available depend on intrinsic sizes.
-  return aSize.IsMaxContent() || aSize.IsMinContent() ||
-         aSize.IsFitContent() || aSize.IsFitContentFunction();
+  return aSize.IsMaxContent() || aSize.IsMinContent() || aSize.IsFitContent() ||
+         aSize.IsFitContentFunction();
 }
 
 bool nsIFrame::CanBeDynamicReflowRoot() const {
@@ -6973,9 +6973,8 @@ nsRect nsIFrame::GetScreenRectInAppUnits() const {
     rootScreenPos.x = NS_round(parentScale * rootPt.x);
     rootScreenPos.y = NS_round(parentScale * rootPt.y);
   } else {
-    nsCOMPtr<nsIWidget> rootWidget;
-    presContext->PresShell()->GetViewManager()->GetRootWidget(
-        getter_AddRefs(rootWidget));
+    nsCOMPtr<nsIWidget> rootWidget =
+        presContext->PresShell()->GetViewManager()->GetRootWidget();
     if (rootWidget) {
       LayoutDeviceIntPoint rootDevPx = rootWidget->WidgetToScreenOffset();
       rootScreenPos.x = presContext->DevPixelsToAppUnits(rootDevPx.x);

layout/xul/nsXULPopupManager.cpp

@@ -1527,8 +1527,8 @@ nsEventStatus nsXULPopupManager::FirePopupShowingEvent(
   // coordinates are relative to the root widget
   nsPresContext* rootPresContext = aPresContext->GetRootPresContext();
   if (rootPresContext) {
-    rootPresContext->PresShell()->GetViewManager()->GetRootWidget(
-        getter_AddRefs(event.mWidget));
+    event.mWidget =
+        rootPresContext->PresShell()->GetViewManager()->GetRootWidget();
   } else {
     event.mWidget = nullptr;
   }

view/nsViewManager.cpp

@@ -903,21 +903,16 @@ void nsViewManager::DecrementDisableRefreshCount() {
   NS_ASSERTION(mRefreshDisableCount >= 0, "Invalid refresh disable count!");
 }
 
-void nsViewManager::GetRootWidget(nsIWidget** aWidget) {
-  if (!mRootView) {
-    *aWidget = nullptr;
-    return;
+already_AddRefed<nsIWidget> nsViewManager::GetRootWidget() {
+  nsCOMPtr<nsIWidget> rootWidget;
+  if (mRootView) {
+    if (mRootView->HasWidget()) {
+      rootWidget = mRootView->GetWidget();
+    } else if (mRootView->GetParent()) {
+      rootWidget = mRootView->GetParent()->GetViewManager()->GetRootWidget();
+    }
   }
-  if (mRootView->HasWidget()) {
-    *aWidget = mRootView->GetWidget();
-    NS_ADDREF(*aWidget);
-    return;
-  }
-  if (mRootView->GetParent()) {
-    mRootView->GetParent()->GetViewManager()->GetRootWidget(aWidget);
-    return;
-  }
-  *aWidget = nullptr;
+  return rootWidget.forget();
 }
 
 LayoutDeviceIntRect nsViewManager::ViewToWidget(nsView* aView,

view/nsViewManager.h

@@ -14,6 +14,7 @@
 #include "nsDeviceContext.h"
 #include "nsTArray.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/AlreadyAddRefed.h"
 #include "mozilla/EventForwards.h"
 
 class nsIWidget;
@@ -281,7 +282,7 @@ class nsViewManager final {
    * Retrieve the widget at the root of the nearest enclosing
    * view manager whose root view has a widget.
    */
-  void GetRootWidget(nsIWidget** aWidget);
+  already_AddRefed<nsIWidget> GetRootWidget();
 
   /**
    * Indicate whether the viewmanager is currently painting

widget/gtk/nsDragService.cpp

@@ -293,8 +293,7 @@ static GtkWindow* GetGtkWindow(dom::Document* aDocument) {
   RefPtr<nsViewManager> vm = presShell->GetViewManager();
   if (!vm) return nullptr;
 
-  nsCOMPtr<nsIWidget> widget;
-  vm->GetRootWidget(getter_AddRefs(widget));
+  nsCOMPtr<nsIWidget> widget = vm->GetRootWidget();
   if (!widget) return nullptr;
 
   GtkWidget* gtkWidget =