Bug 870925 - Followup: Refactor MockAndroidSubmissionClient to own file.
Bug 870925 - Followup: Remove unneeded assertion imports.
Bug 870925 - Followup: Refactor MockHealthReportStorage into MockAndroidSubmissionClient.
Bug 870925 - Followup: Add descriptive MockAndroidSubmissionClient comments.
Bug 870925 - Followup: Fix TestTrackingRequestDelegate tests.
Bug 870925 - Followup: Fix StubDelegate import path.
Bug 870925 - Followup: Throw on provider init failure.
Bug 870925 - Followup: Clarify FieldSpec var name.
Bug 870925 - Followup: Remove unnecessary params.
Bug 870925 - Followup: Fix bug in environment retrieval.

Before, we were registering a detached Environment instance to get the
id when we should have been registering the current environment first.
Bug 870925 - Followup: Uncomment TestAndroidSubmissionClient and fix compile errors.
Bug 870925 - Followup: Fix AndroidSubmissionClient tests (part 1).