UMA stats for MTP file system in Chrome OS Files.app.

BUG=363840

Review URL: https://codereview.chromium.org/267573005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269510 0039d316-1c4b-4281-b951-d872f2087c98

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

@@ -168,6 +168,9 @@ void VolumeInfoToVolumeMetadata(
       volume_metadata->volume_type =
           file_browser_private::VOLUME_TYPE_TESTING;
       break;
+    case NUM_VOLUME_TYPE:
+      NOTREACHED();
+      break;
   }
 
   // Fill device_type iff the volume is removable partition.

chrome/browser/chromeos/file_manager/volume_manager.cc

@@ -11,6 +11,7 @@
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
+#include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/chromeos/drive/drive_integration_service.h"
@@ -111,6 +112,8 @@ std::string VolumeTypeToString(VolumeType type) {
       return "mtp";
     case VOLUME_TYPE_TESTING:
       return "testing";
+    case NUM_VOLUME_TYPE:
+      break;
   }
   NOTREACHED();
   return "";
@@ -801,9 +804,16 @@ void VolumeManager::DoMountEvent(chromeos::MountError error_code,
     return;
   }
 
-  if (error_code == chromeos::MOUNT_ERROR_NONE || volume_info.mount_condition)
+  if (error_code == chromeos::MOUNT_ERROR_NONE || volume_info.mount_condition) {
     mounted_volumes_[volume_info.volume_id] = volume_info;
 
+    if (!is_remounting) {
+      UMA_HISTOGRAM_ENUMERATION("FileBrowser.VolumeType",
+                                volume_info.type,
+                                NUM_VOLUME_TYPE);
+    }
+  }
+
   FOR_EACH_OBSERVER(VolumeManagerObserver,
                     observers_,
                     OnVolumeMounted(error_code, volume_info, is_remounting));

chrome/browser/chromeos/file_manager/volume_manager.h

@@ -40,17 +40,21 @@ namespace file_manager {
 class MountedDiskMonitor;
 class VolumeManagerObserver;
 
-// This manager manages "Drive" and "Downloads" in addition to disks managed
-// by DiskMountManager.
+// Identifiers for volume types managed by Chrome OS file manager.
 enum VolumeType {
-  VOLUME_TYPE_GOOGLE_DRIVE,
+  VOLUME_TYPE_TESTING = -1,  // Used only in tests.
+  VOLUME_TYPE_GOOGLE_DRIVE = 0,
   VOLUME_TYPE_DOWNLOADS_DIRECTORY,
   VOLUME_TYPE_REMOVABLE_DISK_PARTITION,
   VOLUME_TYPE_MOUNTED_ARCHIVE_FILE,
   VOLUME_TYPE_CLOUD_DEVICE,
   VOLUME_TYPE_PROVIDED,  // File system provided by the FileSystemProvider API.
   VOLUME_TYPE_MTP,
-  VOLUME_TYPE_TESTING
+  // The enum values must be kept in sync with FileManagerVolumeType in
+  // tools/metrics/histograms/histograms.xml. Since enums for histograms are
+  // append-only (for keeping the number consistent across versions), new values
+  // for this enum also has to be always appended at the end (i.e., here).
+  NUM_VOLUME_TYPE,
 };
 
 struct VolumeInfo {

tools/metrics/histograms/histograms.xml

@@ -7067,6 +7067,14 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="FileBrowser.VolumeType" enum="FileManagerVolumeType">
+  <owner>kinaba@chromium.org</owner>
+  <summary>
+    Chrome OS File Browser: counts the number of times volumes are mounted for
+    each volume type.
+  </summary>
+</histogram>
+
 <histogram name="GCM.CheckinRequestStatus" enum="GCMCheckinRequestStatus">
   <owner>juyik@chromium.org</owner>
   <summary>Status code of the outcome of a GCM checkin request.</summary>
@@ -35193,6 +35201,16 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="6" label="Error"/>
 </enum>
 
+<enum name="FileManagerVolumeType" type="int">
+  <int value="0" label="Google Drive"/>
+  <int value="1" label="Download Folder"/>
+  <int value="2" label="Removable Disk"/>
+  <int value="3" label="Archive File"/>
+  <int value="4" label="Cloud Device"/>
+  <int value="5" label="FileSystemProvider API"/>
+  <int value="6" label="MTP (Media Transfer Protocol) Device"/>
+</enum>
+
 <enum name="FileType" type="int">
   <int value="0" label="other"/>
   <int value="1" label=".doc"/>