Reland of move configuration policy from chrome build files.

chrome/browser/extensions/BUILD.gn

Index: chrome/browser/extensions/BUILD.gn
diff --git a/chrome/browser/extensions/BUILD.gn b/chrome/browser/extensions/BUILD.gn
index a5124180e620064d4873d990ecc3e36dc3a9826f..35aeeaa9639f780f5cd75a1e0ba8044afa7c1212 100644
--- a/chrome/browser/extensions/BUILD.gn
+++ b/chrome/browser/extensions/BUILD.gn
@@ -47,6 +47,7 @@
     "//components/data_reduction_proxy/proto:data_reduction_proxy_proto",
     "//components/dom_distiller/core",
     "//components/onc",
+    "//components/policy",
     "//components/proximity_auth",
     "//components/resources",
     "//components/strings",
@@ -162,17 +163,6 @@
     }
   }
 
-  if (enable_configuration_policy) {
-    deps += [ "//components/policy" ]
-    sources += [
-      "policy_handlers.cc",
-      "policy_handlers.h",
-    ]
-    sources += rebase_path(gypi_values.chrome_browser_extensions_policy_sources,
-                           ".",
-                           "//chrome")
-  }
-
   if (enable_webrtc) {
     sources += [ "api/webrtc_logging_private/webrtc_logging_private_api.cc" ]
   } else {