Revise the SystemState hierarchy.

* Removed all #includes from SystemState; added includes in .cc files
  that use the various objects (MetricsLibrary, DevicePolicy, etc).

* MockSystemState:

  - Regulated the set of getters/setters: foo() returns the current Foo
    object interface; this object can be overridden by set_foo();
    mock_foo() or fake_foo() returns the default (internal) mock/fake
    equivalent, and fails if it is different from foo() (safety).

  - Make member declaration order consistent with that of API.

  - Removed MOCK_METHOD declarations for two methods and replaced them
    with fake getter/setter. This means that MockSystemState is now
    reduced to a fake, and can be renamed (separate CL). This also means
    that a few tests have a slightly different semantics now.

* All virtual overrides are qualified as such. However, removed the
  'const' method qualified from all getters: it made little sense,
  especially when considering that getters are handing addresses of
  internal mock members.

* Made the UpdateAttempter a contained member of both
  {Real,Mock}SystemState, resolving initialization dependencies. In
  general, the invariant is that all members of the SystemState that
  rely on it being fully populated by the time of their initialization,
  need to export a separate Init() method, that will be called (by the
  SystemState implementation constructor or Init() method) only after
  all members are set.

* Made the mock GPIO handler and connection manager contained members of
  MockSystemState; the destructor could safely be moved.

* Cleanup in UpdateAttempter (part of resolving dependencies):

  - Ordinary member initialization done via default initializers
    (constants) or initializer list in the constructor (parameters).

  - Init() method only does work that cannot be done during
    construction, with appropriate comment documenting the need for it.

  - Better reuse via constructor delegation.

BUG=chromium:358278
TEST=Unit tests.

Change-Id: I96ff6fc7e7400b0a9feb6cc8d4ffe97a51000f91
Reviewed-on: https://chromium-review.googlesource.com/193587
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
diff --git a/payload_state.cc b/payload_state.cc
index 2685130..51041ef 100644
--- a/payload_state.cc
+++ b/payload_state.cc
@@ -10,11 +10,13 @@
 #include <base/strings/string_util.h>
 #include <base/strings/stringprintf.h>
 #include <base/format_macros.h>
+#include <policy/device_policy.h>
 
 #include "update_engine/clock.h"
 #include "update_engine/constants.h"
 #include "update_engine/hardware_interface.h"
 #include "update_engine/install_plan.h"
+#include "update_engine/omaha_request_params.h"
 #include "update_engine/prefs.h"
 #include "update_engine/real_dbus_wrapper.h"
 #include "update_engine/system_state.h"