Power component

Implemented: Symbian::Power exports ReadPowerSnapshot() in <symbian/api/power/power.h>.

Motivation and modernization

The original HAL exposes separately queried integer attributes and a small battery-status enumeration. A caller cannot safely derive a charge percentage or a charging state from those integers. PowerSnapshot uses three independent std::optional fields: power-good, external supply in use, and a typed BatteryCondition. A partial result remains useful without inventing values for unsupported attributes. absl::StatusOr reports when none can be read.

Ownership and cost

native_power.cc owns the legacy HAL header and performs three synchronous queries. The modern adapter maps only documented values; unknown integer values stay unknown. The snapshot owns no native handle and allocates no buffers. It is read on demand, without caching dynamic power state. A caller that needs a bounded event callback should issue the query from a worker.

Decide whether to postpone background sync

Link Symbian::Power. This policy postpones work when the battery is low, empty or needs replacement, unless an external supply is known to be present. An unknown battery produces an unknown decision instead of a guessed percentage.

#include "symbian/api/power/power.h"

absl::StatusOr<std::optional<bool>> ShouldPostponeSync() {
  auto power = symbian::api::power::ReadPowerSnapshot();
  if (!power.ok()) {
    return power.status();
  }
  if (power->external_power == true) {
    return std::optional<bool>{false};
  }
  if (!power->battery) {
    return std::optional<bool>{};
  }
  return std::optional<bool>{*power->battery !=
                             symbian::api::power::BatteryCondition::kGood};
}

The caller decides how to handle an unknown result. External supply here affects work policy only; it does not imply that the battery is charging.

Restrictions

The snapshot is not atomic across its three HAL calls. Change subscriptions and model-specific charging information are unavailable. External power alone is never labelled "charging".