Add support for user actions to the metrics library and the metrics clients.

c_metrics_library.h

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef C_METRICS_LIBRARY_H_
 #define C_METRICS_LIBRARY_H_
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
@@ skipping 10 matching lines @@
 
 // C wrapper for MetricsLibrary::SendToUMA.
 int CMetricsLibrarySendToUMA(CMetricsLibrary handle,
                              const char* name, int sample,
                              int min, int max, int nbuckets);
 
 // C wrapper for MetricsLibrary::SendEnumToUMA.
 int CMetricsLibrarySendEnumToUMA(CMetricsLibrary handle,
                                  const char* name, int sample, int max);
 
+// C wrapper for MetricsLibrary::SendUserActionToUMA.
+int CMetricsLibrarySendUserActionToUMA(CMetricsLibrary handle,
+                                       const char* action);
+
 // C wrapper for MetricsLibrary::AreMetricsEnabled.
 int CMetricsLibraryAreMetricsEnabled(CMetricsLibrary handle);
 
 #if defined(__cplusplus)
 }
 #endif
 #endif  // C_METRICS_LIBRARY_H_