refactor: move GetPrinterList off WebContents (#26518)

filenames.gni

@@ -283,6 +283,7 @@ filenames = {
     "shell/browser/api/electron_api_power_monitor.h",
     "shell/browser/api/electron_api_power_save_blocker.cc",
     "shell/browser/api/electron_api_power_save_blocker.h",
+    "shell/browser/api/electron_api_printing.cc",
     "shell/browser/api/electron_api_protocol.cc",
     "shell/browser/api/electron_api_protocol.h",
     "shell/browser/api/electron_api_screen.cc",

lib/browser/api/web-contents.ts

@@ -123,6 +123,7 @@ const defaultPrintingSetting = {
 
 // JavaScript implementations of WebContents.
 const binding = process._linkedBinding('electron_browser_web_contents');
+const printing = process._linkedBinding('electron_browser_printing');
 const { WebContents } = binding as { WebContents: { prototype: Electron.WebContents } };
 
 WebContents.prototype.send = function (channel, ...args) {
@@ -416,8 +417,10 @@ WebContents.prototype.print = function (options = {}, callback) {
 };
 
 WebContents.prototype.getPrinters = function () {
-  if (this._getPrinters) {
+  // TODO(nornagon): this API has nothing to do with WebContents and should be
-    return this._getPrinters();
+  // moved.
+  if (printing.getPrinterList) {
+    return printing.getPrinterList();
   } else {
     console.error('Error: Printing feature is disabled.');
     return [];

shell/browser/api/electron_api_printing.cc

@@ -0,0 +1,77 @@
+// Copyright (c) 2020 Slack Technologies, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_restrictions.h"
+#include "chrome/browser/browser_process.h"
+#include "gin/converter.h"
+#include "printing/buildflags/buildflags.h"
+#include "shell/common/gin_helper/dictionary.h"
+#include "shell/common/node_includes.h"
+
+#if BUILDFLAG(ENABLE_PRINTING)
+#include "printing/backend/print_backend.h"
+#endif
+
+namespace gin {
+
+#if BUILDFLAG(ENABLE_PRINTING)
+template <>
+struct Converter<printing::PrinterBasicInfo> {
+  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,
+                                   const printing::PrinterBasicInfo& val) {
+    gin_helper::Dictionary dict = gin::Dictionary::CreateEmpty(isolate);
+    dict.Set("name", val.printer_name);
+    dict.Set("displayName", val.display_name);
+    dict.Set("description", val.printer_description);
+    dict.Set("status", val.printer_status);
+    dict.Set("isDefault", val.is_default ? true : false);
+    dict.Set("options", val.options);
+    return dict.GetHandle();
+  }
+};
+#endif
+
+}  // namespace gin
+
+namespace electron {
+
+namespace api {
+
+#if BUILDFLAG(ENABLE_PRINTING)
+printing::PrinterList GetPrinterList() {
+  printing::PrinterList printers;
+  auto print_backend = printing::PrintBackend::CreateInstance(
+      g_browser_process->GetApplicationLocale());
+  {
+    // TODO(deepak1556): Deprecate this api in favor of an
+    // async version and post a non blocing task call.
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    print_backend->EnumeratePrinters(&printers);
+  }
+  return printers;
+}
+#endif
+
+}  // namespace api
+
+}  // namespace electron
+
+namespace {
+
+using electron::api::GetPrinterList;
+
+void Initialize(v8::Local<v8::Object> exports,
+                v8::Local<v8::Value> unused,
+                v8::Local<v8::Context> context,
+                void* priv) {
+  v8::Isolate* isolate = context->GetIsolate();
+  gin_helper::Dictionary dict(isolate, exports);
+#if BUILDFLAG(ENABLE_PRINTING)
+  dict.SetMethod("getPrinterList", base::BindRepeating(&GetPrinterList));
+#endif
+}
+
+}  // namespace
+
+NODE_LINKED_MODULE_CONTEXT_AWARE(electron_browser_printing, Initialize)

shell/browser/api/electron_api_web_contents.cc

@@ -161,8 +161,13 @@
 #if BUILDFLAG(ENABLE_PRINTING)
 #include "chrome/browser/printing/print_view_manager_basic.h"
 #include "components/printing/browser/print_manager_utils.h"
+#include "printing/backend/print_backend.h"  // nogncheck
 #include "printing/mojom/print.mojom.h"
 #include "shell/browser/printing/print_preview_message_handler.h"
+
+#if defined(OS_WIN)
+#include "printing/backend/win_helper.h"
+#endif
 #endif
 
 #if BUILDFLAG(ENABLE_COLOR_CHOOSER)
@@ -185,21 +190,6 @@
 namespace gin {
 
 #if BUILDFLAG(ENABLE_PRINTING)
-template <>
-struct Converter<printing::PrinterBasicInfo> {
-  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,
-                                   const printing::PrinterBasicInfo& val) {
-    gin_helper::Dictionary dict = gin::Dictionary::CreateEmpty(isolate);
-    dict.Set("name", val.printer_name);
-    dict.Set("displayName", val.display_name);
-    dict.Set("description", val.printer_description);
-    dict.Set("status", val.printer_status);
-    dict.Set("isDefault", val.is_default ? true : false);
-    dict.Set("options", val.options);
-    return dict.GetHandle();
-  }
-};
-
 template <>
 struct Converter<printing::mojom::MarginType> {
   static bool FromV8(v8::Isolate* isolate,
@@ -2555,19 +2545,6 @@ void WebContents::Print(gin::Arguments* args) {
                      std::move(callback), device_name, silent));
 }
 
-printing::PrinterList WebContents::GetPrinterList() {
-  printing::PrinterList printers;
-  auto print_backend = printing::PrintBackend::CreateInstance(
-      g_browser_process->GetApplicationLocale());
-  {
-    // TODO(deepak1556): Deprecate this api in favor of an
-    // async version and post a non blocing task call.
-    base::ThreadRestrictions::ScopedAllowIO allow_io;
-    print_backend->EnumeratePrinters(&printers);
-  }
-  return printers;
-}
-
 v8::Local<v8::Promise> WebContents::PrintToPDF(base::DictionaryValue settings) {
   v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
   gin_helper::Promise<v8::Local<v8::Value>> promise(isolate);
@@ -3708,7 +3685,6 @@ v8::Local<v8::ObjectTemplate> WebContents::FillObjectTemplate(
       .SetMethod("getAllSharedWorkers", &WebContents::GetAllSharedWorkers)
 #if BUILDFLAG(ENABLE_PRINTING)
       .SetMethod("_print", &WebContents::Print)
-      .SetMethod("_getPrinters", &WebContents::GetPrinterList)
       .SetMethod("_printToPDF", &WebContents::PrintToPDF)
 #endif
       .SetMethod("_setNextChildWebPreferences",

shell/browser/api/electron_api_web_contents.h

@@ -45,12 +45,7 @@
 #if BUILDFLAG(ENABLE_PRINTING)
 #include "chrome/browser/printing/print_view_manager_basic.h"
 #include "components/printing/common/print_messages.h"
-#include "printing/backend/print_backend.h"  // nogncheck
 #include "shell/browser/printing/print_preview_message_handler.h"
-
-#if defined(OS_WIN)
-#include "printing/backend/win_helper.h"
-#endif
 #endif
 
 #if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
@@ -223,7 +218,6 @@ class WebContents : public gin::Wrappable<WebContents>,
                            bool silent,
                            base::string16 default_printer);
   void Print(gin::Arguments* args);
-  printing::PrinterList GetPrinterList();
   // Print current page as PDF.
   v8::Local<v8::Promise> PrintToPDF(base::DictionaryValue settings);
 #endif

shell/common/node_bindings.cc

@@ -56,6 +56,7 @@
   V(electron_browser_power_monitor)      \
   V(electron_browser_power_save_blocker) \
   V(electron_browser_protocol)           \
+  V(electron_browser_printing)           \
   V(electron_browser_session)            \
   V(electron_browser_system_preferences) \
   V(electron_browser_base_window)        \