adb: Recognize rescue mode.

This CL adds client support to recognize the rescue mode (which will be
served by recovery image). It also allows waiting for a device to enter
rescue mode. The support for the actual rescue commands will be added in
follow-up CLs.

Bug: 128415917
Test: `adb devices` recognizes devices under rescue mode.
Test: `adb wait-for-rescue` waits for device to be in rescue mode.
Change-Id: I367d7339fe68006aba09a1e3db6370d472296676
Merged-In: I367d7339fe68006aba09a1e3db6370d472296676
(cherry picked from commit 55d407ec4a0b23f1e20db298b4989068a820087f)

1 files changed, 2 insertions, 0 deletions

diff --git a/adb.h b/adb.h
index c60dcbc1..3a6f059b 100644
--- a/adb.h
+++ b/adb.h
@@ -107,6 +107,7 @@ enum ConnectionState {
     kCsHost,
     kCsRecovery,
     kCsSideload,
+    kCsRescue,
 };
 
 inline bool ConnectionStateIsOnline(ConnectionState state) {
@@ -116,6 +117,7 @@ inline bool ConnectionStateIsOnline(ConnectionState state) {
         case kCsHost:
         case kCsRecovery:
         case kCsSideload:
+        case kCsRescue:
             return true;
         default:
             return false;