[filesapp] Move SWA BUILD.gn PageHandler and UI into one rule

The PageHandler and UI components can depend on each other, which is a
subject of an upcoming CL.

This CL to avoid the `gn check` errors that would result with separate
build rules for these items in that upcoming CL.

Preparatory patch. No change in behavior.

Bug: 1113981
Tbr: alex
Change-Id: Ifeb988d1ce11e548bcb2b2d56021f2d89d8be526
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2528514Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825679}

chromeos/components/file_manager/BUILD.gn

@@ -5,17 +5,10 @@
 assert(is_chromeos, "File Manager is Chrome OS only")
 assert(!is_official_build, "File Manager is only built for unofficial builds")
 
-static_library("file_manager_page_handler") {
+static_library("file_manager_ui") {
   sources = [
     "file_manager_page_handler.cc",
     "file_manager_page_handler.h",
-  ]
-
-  deps = [ "//chromeos/components/file_manager/mojom" ]
-}
-
-static_library("file_manager_ui") {
-  sources = [
     "file_manager_ui.cc",
     "file_manager_ui.h",
     "file_manager_ui_delegate.h",
@@ -24,7 +17,6 @@ static_library("file_manager_ui") {
   ]
 
   deps = [
-    ":file_manager_page_handler",
     "//base",
     "//chromeos/components/file_manager/mojom",
     "//chromeos/constants",