Reland "[fuchsia] handle RetrySystemUpdate reboot reason"

This reverts commit 0ec4e032.

Reason for revert: so in the reland, we can remove NOTREACHED

Original change's description:
> Revert "[fuchsia] handle RetrySystemUpdate reboot reason"
>
> This reverts commit 394a78b4.
>
> Reason for revert: this breaks something
>
> Original change's description:
> > [fuchsia] handle RetrySystemUpdate reboot reason
> >
> > In this change, we add support for RetrySystemUpdate. Also, we stop
> > mapping `RebootSource::OTA` to `StateControlRebootReason::SystemUpdate`
> > because reboots for system updates should only be called from
> > fuchsia.git -- the code we remove isn't being run anyway.
> >
> > BUG=fuchsia:64591
> > TEST=cast_reboot_unittests
> >
> > Change-Id: Ic15f86d31d3985d2fa5a2a3957c5ca61066cd476
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2600053
> > Reviewed-by: Sergey Volk <servolk@chromium.org>
> > Commit-Queue: Zach Kirschenbaum <zkbaum@google.com>
> > Cr-Commit-Position: refs/heads/master@{#838871}
>
> TBR=spang@chromium.org,servolk@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com,zkbaum@google.com
>
> # Not skipping CQ checks because original CL landed > 1 day ago.
>
> Bug: fuchsia:64591
> Change-Id: I9a2dd0fe105b1750c733925a8320a2f4e71cded2
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611448
> Reviewed-by: Sergey Volk <servolk@chromium.org>
> Commit-Queue: Zach Kirschenbaum <zkbaum@google.com>
> Cr-Commit-Position: refs/heads/master@{#840361}

TBR=spang@chromium.org,servolk@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com,zkbaum@google.com

Bug: fuchsia:64591
Change-Id: I4d6fffa0df883dbb6dae6add7f8e81aedcd0a95c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611526
Commit-Queue: Zach Kirschenbaum <zkbaum@google.com>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840604}

chromecast/system/reboot/reboot_fuchsia.cc

@@ -91,6 +91,9 @@ bool RebootShlib::RebootNow(RebootSource reboot_source) {
       reason = StateControlRebootReason::USER_REQUEST;
       break;
     case RebootSource::OTA:
+      // We expect OTAs to be initiated by the platform via the
+      // fuchsia.hardware.power.statecontrol/Admin FIDL service. In case
+      // non-platform code wants to initiate OTAs too, we also support it here.
       reason = StateControlRebootReason::SYSTEM_UPDATE;
       break;
     case RebootSource::OVERHEAT:
@@ -175,6 +178,7 @@ RebootShlib::RebootSource RebootUtil::GetLastRebootSource() {
     case RebootReason::USER_REQUEST:
       return RebootShlib::RebootSource::API;
     case RebootReason::SYSTEM_UPDATE:
+    case RebootReason::RETRY_SYSTEM_UPDATE:
       return RebootShlib::RebootSource::OTA;
     case RebootReason::HIGH_TEMPERATURE:
       return RebootShlib::RebootSource::OVERHEAT;

chromecast/system/reboot/reboot_fuchsia_test.cc

@@ -236,6 +236,24 @@ TEST_F(RebootFuchsiaTest, GetLastRebootSourceWithoutGranularReason) {
               Eq(RebootShlib::RebootSource::SW_OTHER));
 }
 
+fuchsia::feedback::LastReboot GenerateLastReboot(bool graceful,
+                                                 RebootReason reason) {
+  fuchsia::feedback::LastReboot last_reboot;
+  last_reboot.set_graceful(graceful);
+  last_reboot.set_reason(reason);
+  return last_reboot;
+}
+
+// RetrySystemUpdate must be handled separately because it does not work with
+// the RebootFuchsiaParamTest family of tests. Those tests expect
+// RebootSource::OTA to map to exactly one StateControlRebootReason, which is
+// now not the case.
+TEST_F(RebootFuchsiaTest, RebootReasonRetrySystemUpdateTranslatesFromFuchsia) {
+  SetLastReboot(GenerateLastReboot(true, RebootReason::RETRY_SYSTEM_UPDATE));
+  EXPECT_THAT(RebootUtil::GetLastRebootSource(),
+              Eq(RebootShlib::RebootSource::OTA));
+}
+
 class RebootFuchsiaParamTest : public RebootFuchsiaTest,
                                public ::testing::WithParamInterface<RebootReasonParam> {
  public:
@@ -249,12 +267,7 @@ TEST_P(RebootFuchsiaParamTest, RebootNowSendsFidlRebootReason) {
 }
 
 TEST_P(RebootFuchsiaParamTest, GetLastRebootSourceTranslatesReasonFromFuchsia) {
-  fuchsia::feedback::LastReboot last_reboot;
-  last_reboot.set_graceful(GetParam().graceful);
-  last_reboot.set_reason(GetParam().reason);
-  EXPECT_TRUE(last_reboot.has_graceful());
-  EXPECT_TRUE(last_reboot.has_reason());
-  SetLastReboot(std::move(last_reboot));
+  SetLastReboot(GenerateLastReboot(GetParam().graceful, GetParam().reason));
   EXPECT_THAT(RebootUtil::GetLastRebootSource(), Eq(GetParam().source));
 }