Bug 1751217 Part 2: Change nsDeviceContext::GetDepth to eliminate the outparam. r=emilio

This function always succeeds so there's no reason to maintain an nsresult.

Differential Revision: https://phabricator.services.mozilla.com/D141407

dom/base/nsScreen.cpp

@@ -63,9 +63,7 @@ int32_t nsScreen::GetPixelDepth(ErrorResult& aRv) {
     return -1;
   }
 
-  uint32_t depth;
-  context->GetDepth(depth);
-  return depth;
+  return context->GetDepth();
 }
 
 nsPIDOMWindowOuter* nsScreen::GetOuter() const {

gfx/src/nsDeviceContext.cpp

@@ -211,7 +211,7 @@ already_AddRefed<gfxContext> nsDeviceContext::CreateRenderingContextCommon(
   return pContext.forget();
 }
 
-nsresult nsDeviceContext::GetDepth(uint32_t& aDepth) {
+uint32_t nsDeviceContext::GetDepth() {
   nsCOMPtr<nsIScreen> screen;
   FindScreen(getter_AddRefs(screen));
   if (!screen) {
@@ -219,9 +219,9 @@ nsresult nsDeviceContext::GetDepth(uint32_t& aDepth) {
     screenManager.GetPrimaryScreen(getter_AddRefs(screen));
     MOZ_ASSERT(screen);
   }
-  screen->GetColorDepth(reinterpret_cast<int32_t*>(&aDepth));
-
-  return NS_OK;
+  int32_t depth = 0;
+  screen->GetColorDepth(&depth);
+  return uint32_t(depth);
 }
 
 nsresult nsDeviceContext::GetDeviceSurfaceDimensions(nscoord& aWidth,

gfx/src/nsDeviceContext.h

@@ -110,7 +110,7 @@ class nsDeviceContext final {
   /**
    * Return the bit depth of the device.
    */
-  nsresult GetDepth(uint32_t& aDepth);
+  uint32_t GetDepth();
 
   /**
    * Get the size of the displayable area of the output device

layout/style/nsMediaFeatures.cpp

@@ -157,7 +157,7 @@ uint32_t Gecko_MediaFeatures_GetColorDepth(const Document* aDocument) {
 
   if (!nsContentUtils::ShouldResistFingerprinting(aDocument)) {
     if (nsDeviceContext* dx = GetDeviceContextFor(aDocument)) {
-      dx->GetDepth(depth);
+      depth = dx->GetDepth();
     }
   }