Record UMA statistics for file_stream operations.

net/base/file_stream_metrics.cc

Index: net/base/file_stream_metrics.cc
diff --git a/net/base/file_stream_metrics.cc b/net/base/file_stream_metrics.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b79a2fa7c106a0004729ad732ae05f26faa459b6
--- /dev/null
+++ b/net/base/file_stream_metrics.cc
@@ -0,0 +1,84 @@
+// 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.
+
+#include "net/base/file_stream_metrics.h"
+
+#include <string>
+#if defined(OS_WIN)
+#include <windows.h>

[cbentzel, 2011/08/16 13:36:02]

You shouldn't need to include windows.h here. 

[ahendrickson, 2011/08/17 20:12:04]

Done.

+#endif
+
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "net/base/file_stream.h"

[cbentzel, 2011/08/16 13:36:02]

You shouldn't need to include file_stream.h either. 

[ahendrickson, 2011/08/17 20:12:04]

Done.

+
+namespace net {
+
+namespace {
+
+void RecordFileErrorTypeCount(FileErrorSource type) {
+  UMA_HISTOGRAM_ENUMERATION(
+      "FileErrorType.Counts", type, FILE_ERROR_SOURCE_COUNT);
+}
+
+}  // namespace
+
+void RecordFileError(int error, FileErrorSource type) {
+  RecordFileErrorTypeCount(type);
+
+  DLOG(WARNING) << "() " << "Recording error " << error

[cbentzel, 2011/08/16 13:36:02]

Remove this. 

[ahendrickson, 2011/08/17 20:12:04]

Done.

+                << " of type " << type;
+
+  unsigned int max_error = (1U << 14) - 2;  // Histogram limit.
+
+  error = ReduceErrorRange(error);
+  max_error = MaxError();

[cbentzel, 2011/08/16 13:36:02]

You might want to document that this can never change during the run of a
program.

[ahendrickson, 2011/08/17 20:12:04]

Done.

+
+  switch(type) {
+    case FILE_ERROR_SOURCE_IS_NOT_OPEN:
+      {

[cbentzel, 2011/08/16 13:36:02]

Nit: Do you need these braces? May be less vertical space without. 

[ahendrickson, 2011/08/17 20:12:04]

Done.

+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.NotOpen", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_OPEN:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.Open", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_WRITE:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.Write", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_READ:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.Read", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_SEEK:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.Seek", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_FLUSH:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.Flush", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_SET_EOF:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.SetEof", error, max_error);
+        break;
+      }
+    case FILE_ERROR_SOURCE_GET_SIZE:
+      {
+        UMA_HISTOGRAM_ENUMERATION("FileErrorSource.GetSize", error, max_error);
+        break;
+      }
+    default:
+      break;
+  }
+}
+
+}  // namespace net