Add the C++ fake_dmserver to replace python server

Replace the old python policy test server and use proto messages
directly to set the policies.

Bug: b/215330111
Change-Id: Iedbebe93031c738f82f5dd4a54a13e5802cab92f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3436546
Reviewed-by: Sergiy Belozorov <sergiyb@chromium.org>
Reviewed-by: Roman Sorokin <rsorokin@chromium.org>
Commit-Queue: Mohamed Omar <mohamedaomar@google.com>
Reviewed-by: Victor-Gabriel Savu <vsavu@google.com>
Cr-Commit-Position: refs/heads/main@{#1030970}

components/policy/test_support/BUILD.gn

@@ -51,6 +51,12 @@ static_library("test_support") {
     "test_server_helpers.cc",
     "test_server_helpers.h",
   ]
+  if (is_chromeos) {
+    sources += [
+      "fake_dmserver.cc",
+      "fake_dmserver.h",
+    ]
+  }
 
   public_deps = [ "//net:test_support" ]
   deps = [
@@ -66,6 +72,23 @@ static_library("test_support") {
   ]
 }
 
+if (is_chromeos) {
+  executable("fake_dmserver") {
+    testonly = true
+    output_name = "fake_dmserver"
+    sources = [ "fake_dmserver_main.cc" ]
+    public_deps = [ "//net:test_support" ]
+    deps = [
+      ":test_support",
+      "//base",
+      "//google_apis:google_apis",
+      "//net",
+      "//third_party/private_membership:private_membership_proto",
+      "//third_party/re2:re2",
+    ]
+  }
+}
+
 source_set("unittests") {
   testonly = true
 
@@ -95,6 +118,10 @@ source_set("unittests") {
     "signature_provider_unittest.cc",
   ]
 
+  if (is_chromeos) {
+    sources += [ "fake_dmserver_unittest.cc" ]
+  }
+
   deps = [
     ":test_support",
     "//components/policy/core/common:common_constants",

components/policy/test_support/embedded_policy_test_server.h

@@ -68,7 +68,7 @@ class EmbeddedPolicyTestServer {
   virtual ~EmbeddedPolicyTestServer();
 
   // Initializes and waits until the server is ready to accept requests.
-  bool Start();
+  virtual bool Start();
 
   ClientStorage* client_storage() const { return client_storage_.get(); }
 
@@ -100,11 +100,12 @@ class EmbeddedPolicyTestServer {
                             const std::string& raw_policy);
 #endif  // !BUILDFLAG(IS_ANDROID) && !BUILDFLAG(IS_IOS)
 
- private:
+ protected:
   // Default request handler.
-  std::unique_ptr<net::test_server::HttpResponse> HandleRequest(
+  virtual std::unique_ptr<net::test_server::HttpResponse> HandleRequest(
       const net::test_server::HttpRequest& request);
 
+ private:
   // Request handler for external policy data.
   std::unique_ptr<net::test_server::HttpResponse>
   HandleExternalPolicyDataRequest(const GURL& request);