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..e5afedbcd3487691a40bd9b95ed0ea3455f71372 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 +326,25 @@ 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_, "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_, nullptr));
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError", 1);
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError.test", 0);
+  EXPECT_FALSE(
+      ImportantFileWriter::WriteFileAtomically(invalid_file_, nullptr, "test"));
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError", 1);
+  histogram_tester.ExpectTotalCount("ImportantFile.FileCreateError.test", 1);
+}
+
 }  // namespace base