diff --git a/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc b/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
index 8857ecc..5787e53 100644
--- a/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
+++ b/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
@@ -21,16 +21,12 @@
 #include "mojo/edk/embedder/platform_handle.h"
 #include "mojo/edk/embedder/platform_handle_vector.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
+#include "mojo/edk/test/scoped_test_dir.h"
 #include "mojo/edk/test/test_utils.h"
 #include "mojo/edk/util/scoped_file.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-#if defined(OS_ANDROID)
-#include "base/android/path_utils.h"
-#include "base/files/file_path.h"
-#endif
-
 namespace mojo {
 namespace embedder {
 namespace {
@@ -42,22 +38,6 @@
   CHECK_EQ(poll(&pfds, 1, -1), 1);
 }
 
-FILE* NewTmpFile() {
-#if defined(OS_ANDROID)
-  base::FilePath tmpdir;
-  if (!base::android::GetCacheDirectory(&tmpdir))
-    return nullptr;
-  std::string templ = tmpdir.Append("XXXXXXXX").value();
-  int fd = mkstemp(const_cast<char*>(templ.c_str()));
-  if (fd == -1)
-    return nullptr;
-  CHECK(unlink(templ.c_str()) == 0);
-  return fdopen(fd, "w+");
-#else
-  return tmpfile();
-#endif
-}
-
 class PlatformChannelPairPosixTest : public testing::Test {
  public:
   PlatformChannelPairPosixTest() {}
@@ -147,6 +127,8 @@
 }
 
 TEST_F(PlatformChannelPairPosixTest, SendReceiveFDs) {
+  mojo::test::ScopedTestDir test_dir;
+
   static const char kHello[] = "hello";
 
   PlatformChannelPair channel_pair;
@@ -166,7 +148,7 @@
     const char c = '0' + (i % 10);
     ScopedPlatformHandleVectorPtr platform_handles(new PlatformHandleVector);
     for (size_t j = 1; j <= i; j++) {
-      util::ScopedFILE fp(NewTmpFile());
+      util::ScopedFILE fp(test_dir.CreateFile());
       ASSERT_TRUE(fp);
       ASSERT_EQ(j, fwrite(std::string(j, c).data(), 1, j, fp.get()));
       platform_handles->push_back(
@@ -208,6 +190,8 @@
 }
 
 TEST_F(PlatformChannelPairPosixTest, AppendReceivedFDs) {
+  mojo::test::ScopedTestDir test_dir;
+
   static const char kHello[] = "hello";
 
   PlatformChannelPair channel_pair;
@@ -217,7 +201,7 @@
   const std::string file_contents("hello world");
 
   {
-    util::ScopedFILE fp(NewTmpFile());
+    util::ScopedFILE fp(test_dir.CreateFile());
     ASSERT_TRUE(fp);
     ASSERT_EQ(file_contents.size(),
               fwrite(file_contents.data(), 1, file_contents.size(), fp.get()));
diff --git a/mojo/edk/system/multiprocess_message_pipe_unittest.cc b/mojo/edk/system/multiprocess_message_pipe_unittest.cc
index 9a03bc9..02b6465 100644
--- a/mojo/edk/system/multiprocess_message_pipe_unittest.cc
+++ b/mojo/edk/system/multiprocess_message_pipe_unittest.cc
@@ -10,9 +10,6 @@
 #include <vector>
 
 #include "base/bind.h"
-#include "base/files/file_path.h"
-#include "base/files/file_util.h"
-#include "base/files/scoped_temp_dir.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "build/build_config.h"  // TODO(vtl): Remove this.
@@ -26,6 +23,7 @@
 #include "mojo/edk/system/raw_channel.h"
 #include "mojo/edk/system/shared_buffer_dispatcher.h"
 #include "mojo/edk/system/test_utils.h"
+#include "mojo/edk/test/scoped_test_dir.h"
 #include "mojo/edk/test/test_utils.h"
 #include "mojo/edk/util/scoped_file.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -447,8 +445,7 @@
       public testing::WithParamInterface<size_t> {};
 
 TEST_P(MultiprocessMessagePipeTestWithPipeCount, PlatformHandlePassing) {
-  base::ScopedTempDir temp_dir;
-  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  mojo::test::ScopedTestDir test_dir;
 
   helper()->StartChild("CheckPlatformHandleFile");
 
@@ -461,9 +458,7 @@
 
   size_t pipe_count = GetParam();
   for (size_t i = 0; i < pipe_count; ++i) {
-    base::FilePath unused;
-    util::ScopedFILE fp(
-        CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
+    util::ScopedFILE fp(test_dir.CreateFile());
     const std::string world("world");
     CHECK_EQ(fwrite(&world[0], 1, world.size(), fp.get()), world.size());
     fflush(fp.get());
diff --git a/mojo/edk/system/platform_handle_dispatcher_unittest.cc b/mojo/edk/system/platform_handle_dispatcher_unittest.cc
index f3426a2..ecc4d3e 100644
--- a/mojo/edk/system/platform_handle_dispatcher_unittest.cc
+++ b/mojo/edk/system/platform_handle_dispatcher_unittest.cc
@@ -6,10 +6,8 @@
 
 #include <stdio.h>
 
-#include "base/files/file_path.h"
-#include "base/files/file_util.h"
-#include "base/files/scoped_temp_dir.h"
 #include "base/memory/ref_counted.h"
+#include "mojo/edk/test/scoped_test_dir.h"
 #include "mojo/edk/test/test_utils.h"
 #include "mojo/edk/util/scoped_file.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -19,14 +17,11 @@
 namespace {
 
 TEST(PlatformHandleDispatcherTest, Basic) {
-  base::ScopedTempDir temp_dir;
-  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  mojo::test::ScopedTestDir test_dir;
 
   static const char kHelloWorld[] = "hello world";
 
-  base::FilePath unused;
-  util::ScopedFILE fp(
-      CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
+  util::ScopedFILE fp(test_dir.CreateFile());
   ASSERT_TRUE(fp);
   EXPECT_EQ(sizeof(kHelloWorld),
             fwrite(kHelloWorld, 1, sizeof(kHelloWorld), fp.get()));
@@ -62,14 +57,11 @@
 }
 
 TEST(PlatformHandleDispatcherTest, CreateEquivalentDispatcherAndClose) {
-  base::ScopedTempDir temp_dir;
-  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  mojo::test::ScopedTestDir test_dir;
 
   static const char kFooBar[] = "foo bar";
 
-  base::FilePath unused;
-  util::ScopedFILE fp(
-      CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
+  util::ScopedFILE fp(test_dir.CreateFile());
   EXPECT_EQ(sizeof(kFooBar), fwrite(kFooBar, 1, sizeof(kFooBar), fp.get()));
 
   scoped_refptr<PlatformHandleDispatcher> dispatcher =
diff --git a/mojo/edk/system/raw_channel_unittest.cc b/mojo/edk/system/raw_channel_unittest.cc
index 42ffb9f..084ab86 100644
--- a/mojo/edk/system/raw_channel_unittest.cc
+++ b/mojo/edk/system/raw_channel_unittest.cc
@@ -10,9 +10,6 @@
 #include <vector>
 
 #include "base/bind.h"
-#include "base/files/file_path.h"
-#include "base/files/file_util.h"
-#include "base/files/scoped_temp_dir.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -26,6 +23,7 @@
 #include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/test_utils.h"
 #include "mojo/edk/system/transport_data.h"
+#include "mojo/edk/test/scoped_test_dir.h"
 #include "mojo/edk/test/test_io_thread.h"
 #include "mojo/edk/test/test_utils.h"
 #include "mojo/edk/util/scoped_file.h"
@@ -794,8 +792,7 @@
 };
 
 TEST_F(RawChannelTest, ReadWritePlatformHandles) {
-  base::ScopedTempDir temp_dir;
-  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  mojo::test::ScopedTestDir test_dir;
 
   WriteOnlyRawChannelDelegate write_delegate;
   scoped_ptr<RawChannel> rc_write(RawChannel::Create(handles[0].Pass()));
@@ -809,12 +806,9 @@
                                base::Bind(&InitOnIOThread, rc_read.get(),
                                           base::Unretained(&read_delegate)));
 
-  base::FilePath unused;
-  util::ScopedFILE fp1(
-      base::CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
+  util::ScopedFILE fp1(test_dir.CreateFile());
   EXPECT_EQ(1u, fwrite("1", 1, 1, fp1.get()));
-  util::ScopedFILE fp2(
-      base::CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
+  util::ScopedFILE fp2(test_dir.CreateFile());
   EXPECT_EQ(1u, fwrite("2", 1, 1, fp2.get()));
 
   {
diff --git a/mojo/edk/system/remote_message_pipe_unittest.cc b/mojo/edk/system/remote_message_pipe_unittest.cc
index 146848f..26c5bf8 100644
--- a/mojo/edk/system/remote_message_pipe_unittest.cc
+++ b/mojo/edk/system/remote_message_pipe_unittest.cc
@@ -9,9 +9,6 @@
 #include <vector>
 
 #include "base/bind.h"
-#include "base/files/file_path.h"
-#include "base/files/file_util.h"
-#include "base/files/scoped_temp_dir.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
@@ -30,6 +27,7 @@
 #include "mojo/edk/system/shared_buffer_dispatcher.h"
 #include "mojo/edk/system/test_utils.h"
 #include "mojo/edk/system/waiter.h"
+#include "mojo/edk/test/scoped_test_dir.h"
 #include "mojo/edk/test/test_io_thread.h"
 #include "mojo/edk/test/test_utils.h"
 #include "mojo/edk/util/scoped_file.h"
@@ -1011,8 +1009,7 @@
 }
 
 TEST_F(RemoteMessagePipeTest, PlatformHandlePassing) {
-  base::ScopedTempDir temp_dir;
-  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  mojo::test::ScopedTestDir test_dir;
 
   static const char kHello[] = "hello";
   static const char kWorld[] = "world";
@@ -1026,9 +1023,7 @@
   scoped_refptr<MessagePipe> mp1(MessagePipe::CreateProxyLocal(&ep1));
   BootstrapChannelEndpoints(ep0, ep1);
 
-  base::FilePath unused;
-  util::ScopedFILE fp(
-      base::CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
+  util::ScopedFILE fp(test_dir.CreateFile());
   EXPECT_EQ(sizeof(kHello), fwrite(kHello, 1, sizeof(kHello), fp.get()));
   // We'll try to pass this dispatcher, which will cause a |PlatformHandle| to
   // be passed.
diff --git a/mojo/edk/test/BUILD.gn b/mojo/edk/test/BUILD.gn
index b91cc5f..cbe6e26 100644
--- a/mojo/edk/test/BUILD.gn
+++ b/mojo/edk/test/BUILD.gn
@@ -13,6 +13,8 @@
     "multiprocess_test_helper.h",
     "scoped_ipc_support.cc",
     "scoped_ipc_support.h",
+    "scoped_test_dir.cc",
+    "scoped_test_dir.h",
     "test_io_thread.cc",
     "test_io_thread.h",
     "test_utils.h",
diff --git a/mojo/edk/test/scoped_test_dir.cc b/mojo/edk/test/scoped_test_dir.cc
new file mode 100644
index 0000000..5bd768b
--- /dev/null
+++ b/mojo/edk/test/scoped_test_dir.cc
@@ -0,0 +1,27 @@
+// Copyright 2015 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 "mojo/edk/test/scoped_test_dir.h"
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/logging.h"
+
+namespace mojo {
+namespace test {
+
+ScopedTestDir::ScopedTestDir() {
+  CHECK(temp_dir_.CreateUniqueTempDir());
+}
+
+ScopedTestDir::~ScopedTestDir() {}
+
+util::ScopedFILE ScopedTestDir::CreateFile() {
+  base::FilePath unused;
+  return util::ScopedFILE(
+      base::CreateAndOpenTemporaryFileInDir(temp_dir_.path(), &unused));
+}
+
+}  // namespace test
+}  // namespace mojo
diff --git a/mojo/edk/test/scoped_test_dir.h b/mojo/edk/test/scoped_test_dir.h
new file mode 100644
index 0000000..4db372f
--- /dev/null
+++ b/mojo/edk/test/scoped_test_dir.h
@@ -0,0 +1,33 @@
+// Copyright 2015 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.
+
+#ifndef MOJO_EDK_TEST_SCOPED_TEST_DIR_H_
+#define MOJO_EDK_TEST_SCOPED_TEST_DIR_H_
+
+#include "base/files/scoped_temp_dir.h"
+#include "mojo/edk/util/scoped_file.h"
+#include "mojo/public/cpp/system/macros.h"
+
+namespace mojo {
+namespace test {
+
+// Creates/destroyes a temporary directory for test purposes. (Unlike
+// |base::ScopedTempDir|, this automatically creates the temporary directory.)
+class ScopedTestDir {
+ public:
+  ScopedTestDir();
+  ~ScopedTestDir();
+
+  util::ScopedFILE CreateFile();
+
+ private:
+  base::ScopedTempDir temp_dir_;
+
+  MOJO_DISALLOW_COPY_AND_ASSIGN(ScopedTestDir);
+};
+
+}  // namespace test
+}  // namespace mojo
+
+#endif  // MOJO_EDK_TEST_SCOPED_TEST_DIR_H_