Record mount and unmount errors to UMA.

BUG=873903

Change-Id: I2682b57782944dd61365d8f1b698aa53a604fb5c
Reviewed-on: https://chromium-review.googlesource.com/1177208
Commit-Queue: Anand Mistry <amistry@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Robert Kaplow (slow) <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584368}

chrome/browser/chromeos/extensions/file_manager/event_router.cc

@@ -175,6 +175,9 @@ MountErrorToMountCompletedStatus(chromeos::MountError error) {
           MOUNT_COMPLETED_STATUS_ERROR_UNSUPPORTED_FILESYSTEM;
     case chromeos::MOUNT_ERROR_INVALID_ARCHIVE:
       return file_manager_private::MOUNT_COMPLETED_STATUS_ERROR_INVALID_ARCHIVE;
+    // Not a real error.
+    case chromeos::MOUNT_ERROR_COUNT:
+      NOTREACHED();
   }
   NOTREACHED();
   return file_manager_private::MOUNT_COMPLETED_STATUS_NONE;

chromeos/dbus/cros_disks_client.cc

@@ -16,6 +16,7 @@
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/macros.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/observer_list.h"
 #include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
@@ -325,7 +326,11 @@ class CrosDisksClientImpl : public CrosDisksClient {
 
   // Handles the result of Unmount and calls |callback| or |error_callback|.
   void OnUnmount(UnmountCallback callback, dbus::Response* response) {
+    const char kUnmountHistogramName[] = "CrosDisksClient.UnmountError";
+
     if (!response) {
+      UMA_HISTOGRAM_ENUMERATION(kUnmountHistogramName, MOUNT_ERROR_UNKNOWN,
+                                MOUNT_ERROR_COUNT);
       std::move(callback).Run(MOUNT_ERROR_UNKNOWN);
       return;
     }
@@ -345,6 +350,8 @@ class CrosDisksClientImpl : public CrosDisksClient {
       mount_error = CrosDisksMountErrorToChromeMountError(
           static_cast<cros_disks::MountErrorType>(error_code));
     }
+    UMA_HISTOGRAM_ENUMERATION(kUnmountHistogramName, mount_error,
+                              MOUNT_ERROR_COUNT);
     std::move(callback).Run(mount_error);
   }
 
@@ -437,6 +444,8 @@ class CrosDisksClientImpl : public CrosDisksClient {
       return;
     }
 
+    UMA_HISTOGRAM_ENUMERATION("CrosDisksClient.MountCompletedError",
+                              entry.error_code(), MOUNT_ERROR_COUNT);
     for (auto& observer : observer_list_)
       observer.OnMountCompleted(entry);
   }

chromeos/dbus/cros_disks_client.h

@@ -51,6 +51,8 @@ enum DeviceType {
 
 // Mount error code used by cros-disks.
 // These values are not the same as cros_disks::MountErrorType.
+// These values are persisted to logs. Entries should not be renumbered and
+// numeric values should never be reused.
 enum MountError {
   MOUNT_ERROR_NONE,
   MOUNT_ERROR_UNKNOWN,
@@ -69,6 +71,7 @@ enum MountError {
   MOUNT_ERROR_UNKNOWN_FILESYSTEM,
   MOUNT_ERROR_UNSUPPORTED_FILESYSTEM,
   MOUNT_ERROR_INVALID_ARCHIVE,
+  MOUNT_ERROR_COUNT,
 };
 
 // Rename error reported by cros-disks.

tools/metrics/histograms/enums.xml

@@ -8654,6 +8654,26 @@ Called by update_net_error_codes.py.-->
   <int value="5" label="Gzip-compressed Tar"/>
 </enum>
 
+<enum name="CrosDisksClientMountError">
+  <int value="0" label="Success"/>
+  <int value="1" label="Unknown"/>
+  <int value="2" label="Internal"/>
+  <int value="3" label="Invalid argument"/>
+  <int value="4" label="Invalid path"/>
+  <int value="5" label="Path already mounted"/>
+  <int value="6" label="Path not mounted"/>
+  <int value="7" label="Directory creation failed"/>
+  <int value="8" label="Invalid mount options"/>
+  <int value="9" label="Invalid unmount options"/>
+  <int value="10" label="Insufficient permissions"/>
+  <int value="11" label="Mount program not found"/>
+  <int value="12" label="Mount program failed"/>
+  <int value="13" label="Invalid device path"/>
+  <int value="14" label="Unknown filesystem"/>
+  <int value="15" label="Unsupported filesystem"/>
+  <int value="16" label="Invalid archive"/>
+</enum>
+
 <enum name="CrosDisksDeviceMediaType">
   <int value="0" label="Unknown"/>
   <int value="1" label="USB Drive"/>

tools/metrics/histograms/histograms.xml

@@ -15142,6 +15142,23 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="CrosDisksClient.MountCompletedError"
+    enum="CrosDisksClientMountError">
+  <owner>amistry@chromium.org</owner>
+  <summary>
+    The error code of disk mount signals received from the Chrome OS cros-disks
+    daemon.
+  </summary>
+</histogram>
+
+<histogram name="CrosDisksClient.UnmountError" enum="CrosDisksClientMountError">
+  <owner>amistry@chromium.org</owner>
+  <summary>
+    The error code of disk unmount operations returned from the Chrome OS
+    cros-disks daemon.
+  </summary>
+</histogram>
+
 <histogram name="CrosFirstRun.DialogShown">
   <owner>alemate@chromium.org</owner>
   <summary>