Move web modal dialog manager files into the constrained_window component.

components/constrained_window/BUILD.gn

Index: components/constrained_window/BUILD.gn
diff --git a/components/constrained_window/BUILD.gn b/components/constrained_window/BUILD.gn
index 8e0952e0763484aea20c5ab91e9465da9fe55bb0..084526953a659f562139603ef0f0208bcb6b9b00 100644
--- a/components/constrained_window/BUILD.gn
+++ b/components/constrained_window/BUILD.gn
@@ -2,19 +2,35 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/ui.gni")
+
 source_set("constrained_window") {
   sources = [
     "constrained_window_views.cc",
     "constrained_window_views.h",
     "constrained_window_views_client.h",
+    "native_web_contents_modal_dialog_manager_views.cc",
+    "native_web_contents_modal_dialog_manager_views.h",
   ]
 
+  if (!is_mac || mac_views_browser) {
+    sources += [ "web_contents_modal_dialog_manager_views.cc" ]
+  }
+
   deps = [
     "//components/guest_view/browser",
     "//components/web_modal",
+    "//content/public/browser",
     "//skia",
     "//ui/views",
   ]
+
+  if (use_aura) {
+    deps += [
+      "//ui/aura",
+      "//ui/wm",
+    ]
+  }
 }
 
 source_set("unit_tests") {