Extend WavReader and WavWriter API.

Add ability to read and write wav files using rtc::PlatformFile instead
of file name.

Bug: webrtc:8946
Change-Id: If18d9465f2155a33547f800edbdac45971a0e878
Reviewed-on: https://webrtc-review.googlesource.com/61424
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22497}
diff --git a/test/testsupport/fileutils_unittest.cc b/test/testsupport/fileutils_unittest.cc
index 79988c0..4c0be26 100644
--- a/test/testsupport/fileutils_unittest.cc
+++ b/test/testsupport/fileutils_unittest.cc
@@ -127,6 +127,19 @@
   remove(temp_filename.c_str());
 }
 
+TEST_F(FileUtilsTest, GenerateTempFilename) {
+  std::string temp_filename = webrtc::test::GenerateTempFilename(
+      webrtc::test::OutputPath(), "TempFilenameTest");
+  ASSERT_FALSE(webrtc::test::FileExists(temp_filename))
+      << "File exists: " << temp_filename;
+  FILE* file = fopen(temp_filename.c_str(), "wb");
+  ASSERT_TRUE(file != NULL) << "Failed to open file: " << temp_filename;
+  ASSERT_GT(fprintf(file, "%s", "Dummy data"), 0)
+      << "Failed to write to file: " << temp_filename;
+  fclose(file);
+  remove(temp_filename.c_str());
+}
+
 // Only tests that the code executes
 #if defined(WEBRTC_IOS)
 #define MAYBE_CreateDir DISABLED_CreateDir