Add UMA private PPAPI interface for UMA logging from NaCl plugin

ppapi/c/private/ppb_uma_private.h

+/* Copyright (c) 2011 The Chromium 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 PPAPI_C_PRIVATE_PPB_UMA_PRIVATE_H_
+#define PPAPI_C_PRIVATE_PPB_UMA_PRIVATE_H_
+
+#include "ppapi/c/pp_stdint.h"
+#include "ppapi/c/pp_var.h"
+
+#define PPB_UMA_PRIVATE_INTERFACE "PPB_UMA(Private);0.1"
+
+struct PPB_UMA_Private {
+  /**
+   * HistogramCustomTimes is a pointer to a function which records a time
+   * sample given in milliseconds in the histogram given by |name|, possibly
+   * creating the histogram if it does not exist.
+   */
+  void (*HistogramCustomTimes)(struct PP_Var name,
+                               int64_t sample,
+                               int64_t min, int64_t max,
+                               uint32_t bucket_count);
+
+  /**
+   * HistogramCustomCounts is a pointer to a function which records a sample
+   * in the histogram given by |name|, possibly creating the histogram if it
+   * does not exist.
+   */
+  void (*HistogramCustomCounts)(struct PP_Var name,
+                                int32_t sample,
+                                int32_t min, int32_t max,
+                                uint32_t bucket_count);
+
+  /**
+   * HistogramEnumeration is a pointer to a function which records a sample
+   * in the histogram given by |name|, possibly creating the histogram if it
+   * does not exist.  The sample represents a value in an enumeration bounded
+   * by |boundary_value|, that is, sample < boundary_value always.
+   */
+  void (*HistogramEnumeration)(struct PP_Var name,
+                               int32_t sample,
+                               int32_t boundary_value);
+};
+
+#endif  /* PPAPI_C_PRIVATE_PPB_UMA_PRIVATE_H_ */