update_engine: More accurate and general method name

This is a small review that merely changes |UpdateAttempter|'s member
function |IsUpdateRunningOrScheduled()| to a more accurate name and
general name of |IsBusyOrUpdateScheduled()|.

BUG=none
TEST=FEATURES="test" emerge-$BOARD update_engine

Change-Id: I4dcce374c86f61e6cee9d060d915110765a70a79
diff --git a/update_attempter_unittest.cc b/update_attempter_unittest.cc
index b69527d..254579c 100644
--- a/update_attempter_unittest.cc
+++ b/update_attempter_unittest.cc
@@ -1710,10 +1710,10 @@
 
 TEST_F(UpdateAttempterTest, UpdateIsNotRunningWhenUpdateAvailable) {
   // Default construction for |waiting_for_scheduled_check_| is false.
-  EXPECT_FALSE(attempter_.IsUpdateRunningOrScheduled());
+  EXPECT_FALSE(attempter_.IsBusyOrUpdateScheduled());
   // Verify in-progress update with UPDATE_AVAILABLE is running
   attempter_.status_ = UpdateStatus::UPDATE_AVAILABLE;
-  EXPECT_TRUE(attempter_.IsUpdateRunningOrScheduled());
+  EXPECT_TRUE(attempter_.IsBusyOrUpdateScheduled());
 }
 
 TEST_F(UpdateAttempterTest, UpdateAttemptFlagsCachedAtUpdateStart) {