MockSystemState: Initialize connection_manager_ member.

Turns out this is not initialized so any code using
connection_manager() will get a garbage pointer when using
MockSystemState (unless set_connection_manager() has been used, of
course).

BUG=chromium:358339
TEST=Unit tests pass.

Change-Id: Ib528613b61130c2ad167999b6d084b12b3883c89
Reviewed-on: https://chromium-review.googlesource.com/192863
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
Tested-by: David Zeuthen <zeuthen@chromium.org>
diff --git a/mock_system_state.cc b/mock_system_state.cc
index fa6622b..0ad110b 100644
--- a/mock_system_state.cc
+++ b/mock_system_state.cc
@@ -26,11 +26,14 @@
   mock_gpio_handler_ = new testing::NiceMock<MockGpioHandler>();
   mock_update_attempter_ = new testing::NiceMock<UpdateAttempterMock>(
       this, &dbus_);
+  mock_connection_manager_ = new testing::NiceMock<MockConnectionManager>(this);
+  connection_manager_ = mock_connection_manager_;
   fake_policy_manager_.Init(FakeState::Construct());
 }
 
 MockSystemState::~MockSystemState() {
   delete mock_gpio_handler_;
+  delete mock_connection_manager_;
 }
 
 UpdateAttempter* MockSystemState::update_attempter() {