Reland "Move webrtc/{base => rtc_base}" (https://codereview.webrtc.org/2877023002)

Reland the base->rtc_base without adding stub headers (will be
done in follow-up CL). This preserves git blame history of all files.

BUG=webrtc:7634
NOTRY=True
TBR=kwiberg@webrtc.org

Change-Id: Iea3bb6f3f67b8374c96337b63e8f5aa3e6181012
Reviewed-on: https://chromium-review.googlesource.com/554611
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18821}

webrtc/rtc_base/fileutils_unittest.cc

@@ -0,0 +1,33 @@
+/*
+ *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <memory>
+
+#include "webrtc/base/fileutils.h"
+#include "webrtc/base/gunit.h"
+#include "webrtc/base/pathutils.h"
+#include "webrtc/base/stream.h"
+
+namespace rtc {
+
+#if defined (WEBRTC_ANDROID)
+// Fails on Android: https://bugs.chromium.org/p/webrtc/issues/detail?id=4364.
+#define MAYBE_FilesystemTest DISABLED_FilesystemTest
+#else
+#define MAYBE_FilesystemTest FilesystemTest
+#endif
+
+// Make sure we can get a temp folder for the later tests.
+TEST(MAYBE_FilesystemTest, GetTemporaryFolder) {
+  Pathname path;
+  EXPECT_TRUE(Filesystem::GetTemporaryFolder(path, true, nullptr));
+}
+
+}  // namespace rtc