Bug 828654 - WIP: Start building HealthReportUploadPolicy.
Bug 828654 - WIP: generateReport.
Bug 828654 - WIP: track failures.
Bug 828654 - WIP: don't upload if background data is not enabled.
Bug 828654 - WIP: don't upload if there is no new data.
Bug 828654 - WIP: reset failure count after success.
Bug 828654 - WIP: factor out BaseHealthReportUploadClient.
Bug 828654 - WIP: slim down HealthReportUploadClient.
Bug 828654 - WIP: remove earliestLastPing from policy and client.
Bug 828654 - WIP: implement Android health report client.