Refactor subresource related variables to a struct

This patch put subresource related variables like baseMipLevel,
levelCount, baseArrayLayer, layerCount into a single struct at
front-end. We have a lot more at backend too, a following patch
will do that.

Bug: dawn:157

Change-Id: Iab5633a4246b6ae89b80c39f5672dbb31d7a3e78
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/22704
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Yunchao He <yunchao.he@intel.com>

src/dawn_native/DawnNative.cpp

@@ -178,8 +178,8 @@ namespace dawn_native {
                                          uint32_t layerCount) {
         dawn_native::TextureBase* textureBase =
             reinterpret_cast<dawn_native::TextureBase*>(texture);
-        return textureBase->IsSubresourceContentInitialized(baseMipLevel, levelCount,
-                                                            baseArrayLayer, layerCount);
+        SubresourceRange range = {baseMipLevel, levelCount, baseArrayLayer, layerCount};
+        return textureBase->IsSubresourceContentInitialized(range);
     }
 
     std::vector<const char*> GetProcMapNamesForTestingInternal();