WebGPU: resolve requestAdapter to null if we fail to get an adapter

This is the correct behavior instead of rejecting the Promise.

Bug: 852089
Change-Id: I847ff4103084be35696705af8bb06bb1ecb701a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2617499Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842143}

content/test/data/gpu/webgpu-context-lost.html

@@ -18,14 +18,9 @@
     }
 
     async function init(canvas, color) {
-      let adapter = null;
-
-      try {
-        adapter = await navigator.gpu.requestAdapter();
-      } catch (err) {
-        // TODO: remove try and catch here once we no longer expect rejections here.
-        // According to the spec, rejection should only happen when invalid stuff is passed in.
-        console.warn("request adapter failed:", err);
+      let adapter = await navigator.gpu.requestAdapter();
+      if (!adapter) {
+        console.warn('Failed to get WebGPU adapter');
       }
 
       let device = await adapter.requestDevice();
@@ -152,4 +147,4 @@
   <div id='container'></div>
 </body>
 
-</html>
\ No newline at end of file
+</html>

third_party/blink/renderer/modules/webgpu/gpu.cc

@@ -184,8 +184,7 @@ ScriptPromise GPU::requestAdapter(ScriptState* script_state,
       // Failed to create context provider, won't be able to request adapter
       // TODO(crbug.com/973017): Collect GPU info and surface context creation
       // error.
-      resolver->Reject(MakeGarbageCollected<DOMException>(
-          DOMExceptionCode::kOperationError, "Fail to request GPUAdapter"));
+      resolver->Resolve(v8::Null(script_state->GetIsolate()));
       return promise;
     } else {
       // Make a new DawnControlClientHolder with the context provider we just
@@ -209,8 +208,7 @@ ScriptPromise GPU::requestAdapter(ScriptState* script_state,
           WTF::Bind(&GPU::OnRequestAdapterCallback, WrapPersistent(this),
                     WrapPersistent(script_state), WrapPersistent(options),
                     WrapPersistent(resolver)))) {
-    resolver->Reject(MakeGarbageCollected<DOMException>(
-        DOMExceptionCode::kOperationError, "Fail to request GPUAdapter"));
+    resolver->Resolve(v8::Null(script_state->GetIsolate()));
   }
 
   return promise;