PM: Shift to signal-based inference of network connection.

Instead of making DBus calls to shill on-demand, and estimating the time
a connection has changed, the RealShillProvider now listens to the
appropriate DBus signal and update its internal state accordingly. Note
that checking for the connection type still requires a DBus call, if the
connection has changed since its type was last checked.

In order to pass all unit tests (including those of PolicyManager and
RealState), there's a substantial portion of DBus mock set up code that
was added. This code will be removed very soon, once we begin injecting
providers into RealState, instead of low-level DBus and/or clock
interfaces.

BUG=chromium:338585
TEST=Unit tests.

Change-Id: Ia7a2f9db18f905f1b7a2cc1234acb31eaa60009e
Reviewed-on: https://chromium-review.googlesource.com/189692
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/policy_manager/real_state_unittest.cc b/policy_manager/real_state_unittest.cc
index 48491d5..13f8db2 100644
--- a/policy_manager/real_state_unittest.cc
+++ b/policy_manager/real_state_unittest.cc
@@ -2,22 +2,34 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// TODO(garnold) Remove once shill DBus constants not needed.
+#include <chromeos/dbus/service_constants.h>
 #include <gtest/gtest.h>
 
 #include "update_engine/fake_clock.h"
 #include "update_engine/mock_dbus_wrapper.h"
 #include "update_engine/policy_manager/real_state.h"
 #include "update_engine/policy_manager/pmtest_utils.h"
+// TODO(garnold) Remove once we stop mocking DBus.
+#include "update_engine/test_utils.h"
 
 using chromeos_update_engine::FakeClock;
+using chromeos_update_engine::GValueNewString;
+using chromeos_update_engine::GValueFree;
 using chromeos_update_engine::MockDBusWrapper;
 using testing::_;
 using testing::NiceMock;
 using testing::Return;
+using testing::SetArgPointee;
 
 namespace {
 
+// TODO(garnold) This whole section gets removed once we mock the shill provider
+// itself in tests.
+
+// Fake dbus-glib objects.
 DBusGConnection* const kFakeConnection = reinterpret_cast<DBusGConnection*>(1);
+DBusGProxy* const kFakeManagerProxy = reinterpret_cast<DBusGProxy*>(2);
 
 }  // namespace
 
@@ -26,9 +38,31 @@
 TEST(PmRealStateTest, InitTest) {
   NiceMock<MockDBusWrapper> mock_dbus;
   FakeClock fake_clock;
-  EXPECT_CALL(mock_dbus, BusGet(_, _)).WillOnce(Return(kFakeConnection));
+
+  // TODO(garnold) Replace this low-level DBus injection with a high-level
+  // mock shill provider.
+  EXPECT_CALL(mock_dbus, BusGet(_, _))
+      .WillOnce(Return(kFakeConnection));
+  EXPECT_CALL(mock_dbus, ProxyNewForName(_, _, _, _))
+      .WillOnce(Return(kFakeManagerProxy));
+  EXPECT_CALL(mock_dbus, ProxyAddSignal_2(_, _, _, _))
+      .WillOnce(Return());
+  EXPECT_CALL(mock_dbus, ProxyConnectSignal(_, _, _, _, _))
+      .WillOnce(Return());
+  auto properties = g_hash_table_new_full(g_str_hash, g_str_equal, free,
+                                          GValueFree);
+  g_hash_table_insert(properties, strdup(shill::kDefaultServiceProperty),
+                      GValueNewString("/"));
+  EXPECT_CALL(mock_dbus, ProxyCall_0_1(_, _, _, _))
+      .WillOnce(DoAll(SetArgPointee<3>(g_hash_table_ref(properties)),
+                      Return(true)));
+
   RealState state(&mock_dbus, &fake_clock);
   EXPECT_TRUE(state.Init());
+
+  // TODO(garnold) Remove this, too.
+  g_hash_table_unref(properties);
+
   // Check that the providers are being initialized.
   PMTEST_ASSERT_NOT_NULL(state.random_provider());
   PMTEST_EXPECT_NOT_NULL(state.random_provider()->var_seed());