Add metrics library tests. Some metrics daemon API cleanup.

src/platform/metrics/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 METRICS_LIBRARY_H_
 #define METRICS_LIBRARY_H_
 
+#include <sys/types.h>
 #include <string>
 
-// TODO(sosa@chromium.org): Add testing for send methods
+#include <gtest/gtest_prod.h>  // for FRIEND_TEST
 
 class MetricsLibraryInterface {
  public:
   virtual void Init() = 0;
   virtual bool SendToUMA(const std::string& name, int sample,
                          int min, int max, int nbuckets) = 0;
   virtual bool SendEnumToUMA(const std::string& name, int sample, int max) = 0;
   virtual ~MetricsLibraryInterface() {}
 };
 
 // Library used to send metrics to both Autotest and Chrome/UMA.
 class MetricsLibrary : public MetricsLibraryInterface {
  public:
+  MetricsLibrary();
+
   // Initializes the library.
   void Init();
 
   // Sends histogram data to Chrome for transport to UMA and returns
   // true on success. This method results in the equivalent of an
   // asynchronous non-blocking RPC to UMA_HISTOGRAM_CUSTOM_COUNTS
   // inside Chrome (see base/histogram.h).
   //
   // |sample| is the sample value to be recorded (|min| <= |sample| < |max|).
   // |min| is the minimum value of the histogram samples (|min| > 0).
@@ skipping 10 matching lines @@
   // inside Chrome (see base/histogram.h).
   //
   // |sample| is the sample value to be recorded (1 <= |sample| < |max|).
   // |max| is the maximum value of the histogram samples.
   // 0 is the implicit underflow bucket.
   // [|max|,infinity) is the implicit overflow bucket.
   bool SendEnumToUMA(const std::string& name, int sample, int max);
 
   // Sends to Autotest and returns true on success.
   static bool SendToAutotest(const std::string& name, int value);
+
+ private:
+  friend class MetricsLibraryTest;
+  FRIEND_TEST(MetricsLibraryTest, FormatChromeMessage);
+  FRIEND_TEST(MetricsLibraryTest, FormatChromeMessageTooLong);
+  FRIEND_TEST(MetricsLibraryTest, SendMessageToChrome);
+  FRIEND_TEST(MetricsLibraryTest, SendMessageToChromeUMAEventsBadFileLocation);
+
+  // Sends message of size |length| to Chrome for transport to UMA and
+  // returns true on success.
+  bool SendMessageToChrome(int32_t length, const char* message);
+
+  // Formats a name/value message for Chrome in |buffer| and returns the
+  // length of the message or a negative value on error.
+  //
+  // Message format is: | LENGTH(binary) | NAME | \0 | VALUE | \0 |
+  //
+  // The arbitrary |format| argument covers the non-LENGTH portion of the
+  // message. The caller is responsible to store the \0 character
+  // between NAME and VALUE (e.g. "%s%c%d", name, '\0', value).
+  int32_t FormatChromeMessage(int32_t buffer_size, char* buffer,
+                              const char *format, ...);
+
+  const char* uma_events_file_;
 };
 
 #endif /* METRICS_LIBRARY_H_ */