Add support for linear/enumeration histograms.

src/platform/metrics/metrics_library.cc

 // 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.
 
 /*
  * metrics_library.cc
  *
  *  Created on: Dec 1, 2009
  *      Author: sosa
  */
@@ skipping 132 matching lines @@
       FormatChromeMessage(kBufferSize, message,
                           "histogram%c%s %d %d %d %d", '\0',
                           name.c_str(), sample, min, max, nbuckets);
 
   if (message_length < 0)
     return false;
 
   // Send the message.
   return SendMessageToChrome(message_length, message);
 }
+
+//static
+bool MetricsLibrary::SendEnumToChrome(const std::string& name, int sample,
+                                      int max) {
+  // Format the message.
+  char message[kBufferSize];
+  int32_t message_length =
+      FormatChromeMessage(kBufferSize, message,
+                          "linearhistogram%c%s %d %d", '\0',
+                          name.c_str(), sample, max);
+
+  if (message_length < 0)
+    return false;
+
+  // Send the message.
+  return SendMessageToChrome(message_length, message);
+}