Add Adapter::GetDeviceType() (integrate vs. discrete vs. CPU)

BUG=chromium:852089
Change-Id: Ia447448392e09c5d604ae038b4758776ed3e66ee
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/5180
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

src/dawn_native/DawnNative.cpp

@@ -41,6 +41,10 @@ namespace dawn_native {
         return mImpl->GetBackendType();
     }
 
+    DeviceType Adapter::GetDeviceType() const {
+        return mImpl->GetDeviceType();
+    }
+
     const PCIInfo& Adapter::GetPCIInfo() const {
         return mImpl->GetPCIInfo();
     }