Add support to read fastboot variable 'off-mode-charge'

Bug: 78793464
Bug: 79480454

Test: fastboot getvar off-mode-charge
Change-Id: I4c40847be292e8e2e420340f81bb624b247bc11b
Merged-In: I4c40847be292e8e2e420340f81bb624b247bc11b
(cherry picked from commit b05d278696cbb25e14085362651999204aa51b40)
diff --git a/fastboot/device/variables.cpp b/fastboot/device/variables.cpp
index 77cd4bc..bcf13a5 100644
--- a/fastboot/device/variables.cpp
+++ b/fastboot/device/variables.cpp
@@ -95,6 +95,28 @@
     return true;
 }
 
+bool GetOffModeChargeState(FastbootDevice* device, const std::vector<std::string>& /* args */,
+                           std::string* message) {
+    auto fastboot_hal = device->fastboot_hal();
+    if (!fastboot_hal) {
+        *message = "Fastboot HAL not found";
+        return false;
+    }
+
+    Result ret;
+    auto ret_val =
+            fastboot_hal->getOffModeChargeState([&](bool off_mode_charging_state, Result result) {
+                *message = off_mode_charging_state ? "1" : "0";
+                ret = result;
+            });
+    if (!ret_val.isOk() || (ret.status != Status::SUCCESS)) {
+        *message = "Unable to get off mode charge state";
+        return false;
+    }
+
+    return true;
+}
+
 bool GetCurrentSlot(FastbootDevice* device, const std::vector<std::string>& /* args */,
                     std::string* message) {
     std::string suffix = device->GetCurrentSlot();