Minor cleanup in ItemContent.

Change-Id: I952319a32b3355b24d2eafae06f8899e024b7033
Remove most deprecated Item construction from ChangeOpsMergeTest.

Change-Id: I57dc37ce3f991b02025b0d01eb6e2c316aabaf3f
Cleanup in EntityContent and derivatives

Change-Id: I5024f20ca052cd91f0f20c7d1b5f1325c4ce4cf8
Merge "Remove most deprecated Item construction from ChangeOpsMergeTest."
Merge "Minor cleanup in ItemContent."
Merge "Cleanup in EntityContent and derivatives"