Add missing components/policy build dependencies

Generated files in components/policy used header files that
they didn't depend on. This oversight caused errors when running
gn check --check-generated (brand new gn feature!)

For instance:
ERROR at //out/Default/gen/components/policy/policy_constants.h:14:11: Include not allowed.
#include "components/policy/core/common/policy_details.h"
          ^---------------------------------------------
It is not in any dependency of
  //components/policy:generated
The include file is in the target(s):
  //components/policy/core/common:internal
which should somehow be reachable.

This CL fixes those errors by listing/allowing necessary dependencies.

An alternative would be to extract policy_details.h and policy_map.h
into a new build target, including everything they depend on.
I didn't investigate how much work that is because of time
constraints.

Bug: 938893
Change-Id: I69775047ae70f15138ad0754f4c4d51bd02c7530
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1527534
Commit-Queue: Daniel Bratell <bratell@opera.com>
Reviewed-by: Lutz Justen <ljusten@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644380}

components/policy/BUILD.gn

@@ -335,6 +335,7 @@ static_library("generated") {
     ":cloud_policy_code_generate",
     ":cloud_policy_proto_generated_compile",
     "//base",
+    "//components/policy/core/common:common_constants",
     "//third_party/protobuf:protobuf_lite",
   ]
 }

components/policy/core/common/BUILD.gn

@@ -170,6 +170,12 @@ jumbo_source_set("internal") {
     "//url",
   ]
 
+  allow_circular_includes_from = [
+    # Generated files use policy_details.h and policy_map.h from this target.
+    # TODO(https://crbug.com/945868) - refactor so we don't have dep cycles.
+    "//components/policy:generated",
+  ]
+
   if (is_win) {
     libs = [
       "netapi32.lib",