dawn_native: Make CreateView's descriptor default to nullptr

This matches the defaults of webgpu.h and allows its use from inside
dawn_native for the implementations of SwapChain.

Bug: dawn:269
Change-Id: Icfe15f1775e78690fe4fb7b871bd0c0365d444e4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/33783
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Stephen White <senorblanco@chromium.org>

src/dawn_native/SwapChain.cpp

@@ -189,7 +189,7 @@ namespace dawn_native {
         // of dawn_native
         mCurrentTexture = AcquireRef(GetNextTextureImpl(&descriptor));
 
-        mCurrentTextureView = mCurrentTexture->CreateView(nullptr);
+        mCurrentTextureView = mCurrentTexture->CreateView();
         return mCurrentTextureView.Get();
     }
 

src/dawn_native/Texture.h

@@ -139,7 +139,7 @@ namespace dawn_native {
                                             const Extent3D& extent) const;
 
         // Dawn API
-        TextureViewBase* CreateView(const TextureViewDescriptor* descriptor);
+        TextureViewBase* CreateView(const TextureViewDescriptor* descriptor = nullptr);
         void Destroy();
 
       protected:

src/dawn_native/metal/SwapChainMTL.mm

@@ -129,7 +129,7 @@ namespace dawn_native { namespace metal {
 
         mTexture = AcquireRef(
             new Texture(ToBackend(GetDevice()), &textureDesc, [*mCurrentDrawable texture]));
-        return mTexture->CreateView(nullptr);
+        return mTexture->CreateView();
     }
 
     void SwapChain::DetachFromSurfaceImpl() {

src/dawn_native/null/DeviceNull.cpp

@@ -383,7 +383,7 @@ namespace dawn_native { namespace null {
         TextureDescriptor textureDesc = GetSwapChainBaseTextureDescriptor(this);
         mTexture = AcquireRef(
             new Texture(GetDevice(), &textureDesc, TextureBase::TextureState::OwnedInternal));
-        return mTexture->CreateView(nullptr);
+        return mTexture->CreateView();
     }
 
     void SwapChain::DetachFromSurfaceImpl() {

src/dawn_native/vulkan/SwapChainVk.cpp

@@ -590,7 +590,7 @@ namespace dawn_native { namespace vulkan {
 
         // In the happy path we can use the swapchain image directly.
         if (!mConfig.needsBlit) {
-            return mTexture->CreateView(nullptr);
+            return mTexture->CreateView();
         }
 
         // The blit texture always perfectly matches what the user requested for the swapchain.
@@ -598,7 +598,7 @@ namespace dawn_native { namespace vulkan {
         TextureDescriptor desc = GetSwapChainBaseTextureDescriptor(this);
         DAWN_TRY_ASSIGN(mBlitTexture,
                         Texture::Create(device, &desc, VK_IMAGE_USAGE_TRANSFER_SRC_BIT));
-        return mBlitTexture->CreateView(nullptr);
+        return mBlitTexture->CreateView();
     }
 
     void SwapChain::DetachFromSurfaceImpl() {