fix: prevent navigator.fonts.query() from crashing

filenames.gni

@@ -388,6 +388,8 @@ filenames = {
     "shell/browser/file_select_helper.cc",
     "shell/browser/file_select_helper.h",
     "shell/browser/file_select_helper_mac.mm",
+    "shell/browser/font/electron_font_access_delegate.cc",
+    "shell/browser/font/electron_font_access_delegate.h",
     "shell/browser/font_defaults.cc",
     "shell/browser/font_defaults.h",
     "shell/browser/javascript_environment.cc",

shell/browser/electron_browser_client.cc

@@ -1646,6 +1646,12 @@ content::BluetoothDelegate* ElectronBrowserClient::GetBluetoothDelegate() {
   return bluetooth_delegate_.get();
 }
 
+content::FontAccessDelegate* ElectronBrowserClient::GetFontAccessDelegate() {
+  if (!font_access_delegate_)
+    font_access_delegate_ = std::make_unique<ElectronFontAccessDelegate>();
+  return font_access_delegate_.get();
+}
+
 void BindBadgeServiceForServiceWorker(
     const content::ServiceWorkerVersionBaseInfo& info,
     mojo::PendingReceiver<blink::mojom::BadgeService> receiver) {

shell/browser/electron_browser_client.h

@@ -20,6 +20,7 @@
 #include "net/ssl/client_cert_identity.h"
 #include "services/metrics/public/cpp/ukm_source_id.h"
 #include "shell/browser/bluetooth/electron_bluetooth_delegate.h"
+#include "shell/browser/font/electron_font_access_delegate.h"
 #include "shell/browser/serial/electron_serial_delegate.h"
 #include "third_party/blink/public/mojom/badging/badging.mojom-forward.h"
 
@@ -87,6 +88,8 @@ class ElectronBrowserClient : public content::ContentBrowserClient,
 
   content::SerialDelegate* GetSerialDelegate() override;
 
+  content::FontAccessDelegate* GetFontAccessDelegate() override;
+
   content::BluetoothDelegate* GetBluetoothDelegate() override;
 
   device::GeolocationManager* GetGeolocationManager() override;
@@ -301,6 +304,7 @@ class ElectronBrowserClient : public content::ContentBrowserClient,
 
   std::unique_ptr<ElectronSerialDelegate> serial_delegate_;
   std::unique_ptr<ElectronBluetoothDelegate> bluetooth_delegate_;
+  std::unique_ptr<ElectronFontAccessDelegate> font_access_delegate_;
 
 #if defined(OS_MAC)
   ElectronBrowserMainParts* browser_main_parts_ = nullptr;

shell/browser/font/electron_font_access_delegate.cc

@@ -0,0 +1,42 @@
+// Copyright (c) 2021 Microsoft, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include <utility>
+
+#include "shell/browser/font/electron_font_access_delegate.h"
+
+#include "base/task/post_task.h"
+#include "chrome/browser/browser_process.h"
+#include "content/public/browser/browser_task_traits.h"
+#include "content/public/browser/font_access_chooser.h"
+#include "content/public/browser/render_frame_host.h"
+
+class ElectronFontAccessChooser : public content::FontAccessChooser {
+ public:
+  explicit ElectronFontAccessChooser(base::OnceClosure close_callback) {
+    base::PostTask(
+        FROM_HERE, {content::BrowserThread::UI},
+        base::BindOnce(
+            [](base::OnceClosure closure) { std::move(closure).Run(); },
+            std::move(close_callback)));
+  }
+  ~ElectronFontAccessChooser() override = default;
+};
+
+ElectronFontAccessDelegate::ElectronFontAccessDelegate() = default;
+ElectronFontAccessDelegate::~ElectronFontAccessDelegate() = default;
+
+std::unique_ptr<content::FontAccessChooser>
+ElectronFontAccessDelegate::RunChooser(
+    content::RenderFrameHost* frame,
+    const std::vector<std::string>& selection,
+    content::FontAccessChooser::Callback callback) {
+  // TODO(codebytere) : implement with proper permissions model.
+  return std::make_unique<ElectronFontAccessChooser>(base::BindOnce(
+      [](content::FontAccessChooser::Callback callback) {
+        std::move(callback).Run(
+            blink::mojom::FontEnumerationStatus::kUnimplemented, {});
+      },
+      std::move(callback)));
+}

shell/browser/font/electron_font_access_delegate.h

@@ -0,0 +1,28 @@
+// Copyright (c) 2021 Microsoft, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef SHELL_BROWSER_FONT_ELECTRON_FONT_ACCESS_DELEGATE_H_
+#define SHELL_BROWSER_FONT_ELECTRON_FONT_ACCESS_DELEGATE_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "content/public/browser/font_access_chooser.h"
+#include "content/public/browser/font_access_delegate.h"
+
+class ElectronFontAccessDelegate : public content::FontAccessDelegate {
+ public:
+  ElectronFontAccessDelegate();
+  ~ElectronFontAccessDelegate() override;
+
+  std::unique_ptr<content::FontAccessChooser> RunChooser(
+      content::RenderFrameHost* frame,
+      const std::vector<std::string>& selection,
+      content::FontAccessChooser::Callback callback) override;
+
+  DISALLOW_COPY_AND_ASSIGN(ElectronFontAccessDelegate);
+};
+
+#endif  // SHELL_BROWSER_FONT_ELECTRON_FONT_ACCESS_DELEGATE_H_