Add logging when a rollback or powerwash notification is shown

Add warning level logging when:
- It's detected that update_engine is downloading a rollback
  image or switching channel.
- Notification about the rollback or channel switch to a more
  stable channel is shown.

Bug: 871759
Change-Id: I930b7a23def82ff239ec8da4feeff9daaf960b37
Reviewed-on: https://chromium-review.googlesource.com/1190882
Commit-Queue: Marton Hunyady <hunyadym@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586754}

chrome/browser/upgrade_detector/upgrade_detector_chromeos.cc

@@ -8,6 +8,7 @@
 
 #include <utility>
 
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/no_destructor.h"
@@ -231,6 +232,10 @@ void UpgradeDetectorChromeos::OnChannelsReceived(std::string current_channel,
                             to_more_stable_channel
                                 ? RollbackReason::kToMoreStableChannel
                                 : RollbackReason::kEnterpriseRollback);
+  LOG(WARNING) << "Device is rolling back, will require powerwash. Reason: "
+               << to_more_stable_channel
+               << ", current_channel: " << current_channel
+               << ", target_channel: " << target_channel;
 
   // ChromeOS shows upgrade arrow once the upgrade becomes available.
   NotifyOnUpgrade();

chromeos/dbus/update_engine_client.cc

@@ -7,12 +7,14 @@
 #include <stdint.h>
 
 #include <algorithm>
+#include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/location.h"
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
@@ -503,11 +505,14 @@ class UpdateEngineClientImpl : public UpdateEngineClient {
     status.new_version = new_version;
     // TODO(hunyadym, https://crbug.com/864672): Add a new DBus call to
     // determine this based on the Omaha response, and not version comparison.
-    status.is_rollback = version_loader::IsRollback(
-        version_loader::GetVersion(version_loader::VERSION_SHORT),
-        status.new_version);
-    if (status.is_rollback)
-      VLOG(1) << "New image is a rollback.";
+    std::string current_version =
+        version_loader::GetVersion(version_loader::VERSION_SHORT);
+    status.is_rollback =
+        version_loader::IsRollback(current_version, status.new_version);
+    if (status.is_rollback) {
+      LOG(WARNING) << "New image is a rollback from " << current_version
+                   << " to " << new_version << ".";
+    }
 
     status.new_size = new_size;