Add additional histograms with suffixes to ImportantFileWriter.

base/files/important_file_writer_unittest.cc

Index: base/files/important_file_writer_unittest.cc
diff --git a/base/files/important_file_writer_unittest.cc b/base/files/important_file_writer_unittest.cc
index 511f5fbf5f408b038aa27687281fd7b695886cbb..899bbc7a55aafe741bc6ec76f1fb47e33749d2c6 100644
--- a/base/files/important_file_writer_unittest.cc
+++ b/base/files/important_file_writer_unittest.cc
@@ -15,6 +15,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
+#include "base/test/histogram_tester.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
@@ -325,4 +326,26 @@ TEST_F(ImportantFileWriterTest, DoScheduledWrite_FailToSerialize) {
   EXPECT_FALSE(PathExists(writer.path()));
 }
 
+TEST_F(ImportantFileWriterTest, WriteFileAtomicallyHistogramSuffixTest) {
+  base::HistogramTester histogram_tester;
+  EXPECT_FALSE(PathExists(file_));
+  EXPECT_TRUE(ImportantFileWriter::WriteFileAtomically(
+      file_, StringPiece("baz"), ".test"));
+  EXPECT_TRUE(PathExists(file_));
+  EXPECT_EQ("baz", GetFileContent(file_));
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError", 0);
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError.test", 0);
+
+  FilePath invalid_file_ = FilePath().AppendASCII("bad/../path");
+  EXPECT_FALSE(PathExists(invalid_file_));
+  EXPECT_FALSE(
+      ImportantFileWriter::WriteFileAtomically(invalid_file_, StringPiece()));
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError", 1);
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError.test", 0);
+  EXPECT_FALSE(ImportantFileWriter::WriteFileAtomically(
+      invalid_file_, StringPiece(), ".test"));
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError", 1);
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError.test", 1);
+}
+
 }  // namespace base