watchdog: Get only the initialized property during reset

Since we switched to resetting the watchdog with a built-in method, we
are only using a single property from the watchdog. Instead of fetching
all the properties and reading just the initialized one, only request
the initialized property from the watchdog.

Change-Id: I5e29b5100629e1ce23f352b0b749a434cd1ab793
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/app/watchdog_service.cpp b/app/watchdog_service.cpp
index 26962dc..898cf77 100644
--- a/app/watchdog_service.cpp
+++ b/app/watchdog_service.cpp
@@ -85,6 +85,30 @@
 }
 
 template <typename T>
+T WatchdogService::getProperty(const std::string& key)
+{
+    bool wasValid = wd_service.isValid(bus);
+    auto request = wd_service.newMethodCall(bus, prop_intf, "Get");
+    request.append(wd_intf, key);
+    auto response = bus.call(request);
+    if (response.is_method_error())
+    {
+        wd_service.invalidate();
+        if (wasValid)
+        {
+            // Retry the request once in case the cached service was stale
+            return getProperty<T>(key);
+        }
+        log<level::ERR>("WatchdogService: Method error getting property",
+                        entry("PROPERTY=%s", key.c_str()));
+        elog<InternalFailure>();
+    }
+    variant<T> value;
+    response.read(value);
+    return get<T>(value);
+}
+
+template <typename T>
 void WatchdogService::setProperty(const std::string& key, const T& val)
 {
     bool wasValid = wd_service.isValid(bus);
@@ -105,6 +129,11 @@
     }
 }
 
+bool WatchdogService::getInitialized()
+{
+    return getProperty<bool>("Initialized");
+}
+
 void WatchdogService::setInitialized(bool initialized)
 {
     setProperty("Initialized", initialized);