Call update_engine_sideload from recovery.

This patch enables sideloading an OTA on A/B devices while running from
recovery. Recovery accepts the same OTA package format as recent
versions of GMS, which consists of .zip file with the payload in it.

Bug: 27178350
TEST=`adb sideload` successfully a full OTA (*)
TEST=Failed to take several invalid payloads (wrong product,
fingerprint, update type, serial, etc).

<small>(*) with no postinstall script.</small>

Change-Id: I951869340100feb5a37e41fac0ee59c10095659e
(cherry picked from commit 4344d636d4)

device.cpp

@@ -16,36 +16,15 @@
 
 #include "device.h"
 
-#if defined(AB_OTA_UPDATER)
-
-static const char* MENU_ITEMS[] = {
-    "Reboot system now",
-    "Reboot to bootloader",
-    "Wipe data/factory reset",
-    "Mount /system",
-    "Run graphics test",
-    "Power off",
-    NULL,
-};
-
-static const Device::BuiltinAction MENU_ACTIONS[] = {
-    Device::REBOOT,
-    Device::REBOOT_BOOTLOADER,
-    Device::WIPE_DATA,
-    Device::MOUNT_SYSTEM,
-    Device::RUN_GRAPHICS_TEST,
-    Device::SHUTDOWN,
-};
-
-#else
-
 static const char* MENU_ITEMS[] = {
     "Reboot system now",
     "Reboot to bootloader",
     "Apply update from ADB",
     "Apply update from SD card",
     "Wipe data/factory reset",
+#ifndef AB_OTA_UPDATER
     "Wipe cache partition",
+#endif  // !AB_OTA_UPDATER
     "Mount /system",
     "View recovery logs",
     "Run graphics test",
@@ -59,14 +38,19 @@ static const Device::BuiltinAction MENU_ACTIONS[] = {
     Device::APPLY_ADB_SIDELOAD,
     Device::APPLY_SDCARD,
     Device::WIPE_DATA,
+#ifndef AB_OTA_UPDATER
     Device::WIPE_CACHE,
+#endif  // !AB_OTA_UPDATER
     Device::MOUNT_SYSTEM,
     Device::VIEW_RECOVERY_LOGS,
     Device::RUN_GRAPHICS_TEST,
     Device::SHUTDOWN,
 };
 
-#endif
+static_assert(sizeof(MENU_ITEMS) / sizeof(MENU_ITEMS[0]) ==
+              sizeof(MENU_ACTIONS) / sizeof(MENU_ACTIONS[0]) + 1,
+              "MENU_ITEMS and MENU_ACTIONS should have the same length, "
+              "except for the extra NULL entry in MENU_ITEMS.");
 
 const char* const* Device::GetMenuItems() {
   return MENU_ITEMS;