Combine boolean MediaDeviceNotifications histograms to an enumerated histogram.

chrome/browser/system_monitor/media_storage_util.cc

Index: chrome/browser/system_monitor/media_storage_util.cc
diff --git a/chrome/browser/system_monitor/media_storage_util.cc b/chrome/browser/system_monitor/media_storage_util.cc
index c6a03ed6c1b057450d8aa2ff3bc0b9c237412a72..78c3ceecd8b8665bd22faa96b1e940a059a9e397 100644
--- a/chrome/browser/system_monitor/media_storage_util.cc
+++ b/chrome/browser/system_monitor/media_storage_util.cc
@@ -11,6 +11,7 @@
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/system_monitor/system_monitor.h"
 #include "content/public/browser/browser_thread.h"
 
@@ -34,6 +35,19 @@ namespace {
 
 typedef std::vector<SystemMonitor::RemovableStorageInfo> RemovableStorageInfo;
 
+// MediaDeviceNotification.DeviceInfo histogram values.
+enum DeviceInfoHistogramBuckets {
+  MASS_STORAGE_DEVICE_NAME_AND_UUID_AVAILABLE,
+  MASS_STORAGE_DEVICE_UUID_MISSING,
+  MASS_STORAGE_DEVICE_NAME_MISSING,
+  MASS_STORAGE_DEVICE_NAME_AND_UUID_MISSING,
+  MTP_STORAGE_DEVICE_NAME_AND_UUID_AVAILABLE,
+  MTP_STORAGE_DEVICE_UUID_MISSING,
+  MTP_STORAGE_DEVICE_NAME_MISSING,
+  MTP_STORAGE_DEVICE_NAME_AND_UUID_MISSING,
+  DEVICE_INFO_BUCKET_BOUNDARY
+};
+
 // Prefix constants for different device id spaces.
 const char kRemovableMassStorageWithDCIMPrefix[] = "dcim:";
 const char kRemovableMassStorageNoDCIMPrefix[] = "nodcim:";
@@ -276,6 +290,29 @@ FilePath MediaStorageUtil::FindDevicePathById(const std::string& device_id) {
 }
 
 // static
+void MediaStorageUtil::RecordDeviceInfoHistogram(bool mass_storage,
+                                                 const std::string& device_uuid,
+                                                 const string16& device_name) {
+  int event_number = 0;

[Lei Zhang, 2012/09/17 20:46:01]

unsigned int? otherwise you'd also want to check for event < 0 on line 307.

[Lei Zhang, 2012/09/17 20:46:01]

I think the numbers are a bit hard to read, but I can't think of anything
significantly better, so meh.

[kmadhusu, 2012/09/17 21:52:20]

Done.

+  if (!mass_storage)
+    event_number = 4;
+
+  if (device_name.empty())
+    event_number += 2;
+
+  if (device_uuid.empty())
+    event_number += 1;
+  enum DeviceInfoHistogramBuckets event =
+      static_cast<enum DeviceInfoHistogramBuckets>(event_number);
+  if (event >= DEVICE_INFO_BUCKET_BOUNDARY) {
+    NOTREACHED();
+    return;
+  }
+  UMA_HISTOGRAM_ENUMERATION("MediaDeviceNotifications.DeviceInfo", event,
+                            DEVICE_INFO_BUCKET_BOUNDARY);
+}
+
+// static
 void MediaStorageUtil::SetGetDeviceInfoFromPathFunctionForTesting(
     GetDeviceInfoFromPathFunction function) {
   g_test_get_device_info_from_path_function = function;