Fix checkstyle errors (2/2)

* Manual style corrections with IDE assistance
* Variable name refactors are done through IDE
* Corrected general style errors such as:
  - "final private var" -> "private final var"
  - "&&", "+", "||" should not be at the end of line
  - Non-static private variable should be like "mVar"
  - Private static variable should be like "sVar"
  - Code file should always end with newline
  - Inherited methods should be annotated with @Override
    and no @hide tags
  - Public methods should always have a JavaDoc entry
  - "int[] array" is preferred over "int array[]"
  - private methods should be accessed without "this."
    when there is no name collisions.
  - "boolean ? true : false" -> boolean
  - "boolean ? false : true" -> !boolean
  - "boolean == true" OR "boolean != false" -> boolean
  - "boolean != true" OR "boolean == false" -> !boolean

Bug: 63596319
Test: make checkbuild, no functional changes
Change-Id: Iabdc2be912a32dd63a53213d175cf1bfef268ccd