Add metrics library tests. Some metrics daemon API cleanup.

src/platform/metrics/metrics_library.h

Index: src/platform/metrics/metrics_library.h
diff --git a/src/platform/metrics/metrics_library.h b/src/platform/metrics/metrics_library.h
index 2a6412cb4cc0c8aca2bc5916230aede75b0730aa..8ae3f5b8c912f5a9c66e2dd775a2375195fdcf4b 100644
--- a/src/platform/metrics/metrics_library.h
+++ b/src/platform/metrics/metrics_library.h
@@ -5,9 +5,10 @@
 #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:
@@ -21,6 +22,8 @@ class MetricsLibraryInterface {
 // Library used to send metrics to both Autotest and Chrome/UMA.
 class MetricsLibrary : public MetricsLibraryInterface {
  public:
+  MetricsLibrary();
+
   // Initializes the library.
   void Init();
 
@@ -51,6 +54,30 @@ class MetricsLibrary : public MetricsLibraryInterface {
 
   // 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_ */