build: fix build with "enable_pdf_viewer=false" (#38421)

* build: fix build with "enable_pdf_viewer=false"

* fixup! build: fix build with "enable_pdf_viewer=false"

BUILD.gn

@@ -773,6 +773,8 @@ source_set("electron_lib") {
     sources += [
       "shell/browser/electron_pdf_web_contents_helper_client.cc",
       "shell/browser/electron_pdf_web_contents_helper_client.h",
+      "shell/browser/extensions/api/pdf_viewer_private/pdf_viewer_private_api.cc",
+      "shell/browser/extensions/api/pdf_viewer_private/pdf_viewer_private_api.h",
     ]
   }
 

filenames.gni

@@ -695,8 +695,6 @@ filenames = {
     "shell/browser/extensions/api/management/electron_management_api_delegate.h",
     "shell/browser/extensions/api/resources_private/resources_private_api.cc",
     "shell/browser/extensions/api/resources_private/resources_private_api.h",
-    "shell/browser/extensions/api/pdf_viewer_private/pdf_viewer_private_api.cc",
-    "shell/browser/extensions/api/pdf_viewer_private/pdf_viewer_private_api.h",
     "shell/browser/extensions/api/runtime/electron_runtime_api_delegate.cc",
     "shell/browser/extensions/api/runtime/electron_runtime_api_delegate.h",
     "shell/browser/extensions/api/streams_private/streams_private_api.cc",