metrics: Add SendUserActionToUMA() to MetricsLibraryMock.

The metrics daemon doesn't support sending user actions, but
I need this exposed through the mock library so I can use
SendUserActionToUMA() in the power manager.

Change-Id: Ie9e3995df9978768477fe46dcb9ebec4d1fff1d5

TEST=built for x86-mario with FEATURES=test; checked that the power manager can now use SendUserActionToUMA()

Review URL:
2 files changed
tree: edb26e5584cd8316691d32e9a51950ebe1e1c2ea
  1. metrics/