Fix some compiler warnings

This CL fixes the following compiler warnings.

- Indirect access to static member
- Access to a non-accessible member of an enclosing type
- Parameter assignment
- Method can be static
- Local variable declaration hides another field or variable
- Value of local variable is not used
- Unused import
- Unused private member
- Unnecessary 'else' statement
- Unnecessary declaration of throw exception
- Redundant type arguments
- Missing '@Override' annotation
- Unused '@SuppressWarning' annotations

Bug: 18003991
Change-Id: Icfebe753e53a2cc621848f769d6a3d7ce501ebc7