[POC-WIP] Link window focus tokens with ExecutionContext.

Source/modules/serviceworkers/ServiceWorkerClient.cpp

Index: Source/modules/serviceworkers/ServiceWorkerClient.cpp
diff --git a/Source/modules/serviceworkers/ServiceWorkerClient.cpp b/Source/modules/serviceworkers/ServiceWorkerClient.cpp
index 794644b59e611b3ea604cb28a42867f1adedef12..9265ae9c494864566a8ac21954953dc61b97aeaf 100644
--- a/Source/modules/serviceworkers/ServiceWorkerClient.cpp
+++ b/Source/modules/serviceworkers/ServiceWorkerClient.cpp
@@ -5,8 +5,12 @@
 #include "config.h"
 #include "modules/serviceworkers/ServiceWorkerClient.h"
 
+#include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ExceptionState.h"
+#include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/SerializedScriptValue.h"
+#include "core/page/WindowFocusAllowedIndicator.h"
+#include "modules/serviceworkers/ServiceWorkerError.h"
 #include "modules/serviceworkers/ServiceWorkerGlobalScopeClient.h"
 #include "public/platform/WebString.h"
 #include "wtf/RefPtr.h"
@@ -35,4 +39,19 @@ void ServiceWorkerClient::postMessage(ExecutionContext* context, PassRefPtr<Seri
     ServiceWorkerGlobalScopeClient::from(context)->postMessageToClient(m_id, messageString, webChannels.release());
 }
 
+ScriptPromise ServiceWorkerClient::focus(ScriptState* scriptState)
+{
+    RefPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromise promise = resolver->promise();
+
+    if (!scriptState->executionContext()->isWindowFocusAllowed()) {
+        resolver->resolve(false);
+        return promise;
+    }
+    scriptState->executionContext()->consumeWindowFocusToken();
+
+    ServiceWorkerGlobalScopeClient::from(scriptState->executionContext())->focus(m_id, new CallbackPromiseAdapter<bool, ServiceWorkerError>(resolver));
+    return promise;
+}
+
 } // namespace blink