Fix system unit tests on Android.

mojo/edk/embedder/platform_channel_pair_posix_unittest.cc

Index: mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
diff --git a/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc b/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
index c7b49c210f0aa20c02c77517bee0da0d0ff1bb67..0b20f4b57b5188ae692b9cca9834e7d1732f667f 100644
--- a/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
+++ b/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
@@ -17,6 +17,7 @@
 
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
+#include "build/build_config.h"
 #include "mojo/edk/embedder/platform_channel_utils_posix.h"
 #include "mojo/edk/embedder/platform_handle.h"
 #include "mojo/edk/embedder/platform_handle_vector.h"
@@ -25,6 +26,11 @@
 #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 {
@@ -36,6 +42,22 @@ void WaitReadable(PlatformHandle h) {
   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() {}
@@ -144,7 +166,7 @@ TEST_F(PlatformChannelPairPosixTest, SendReceiveFDs) {
     const char c = '0' + (i % 10);
     ScopedPlatformHandleVectorPtr platform_handles(new PlatformHandleVector);
     for (size_t j = 1; j <= i; j++) {
-      base::ScopedFILE fp(tmpfile());
+      base::ScopedFILE fp(NewTmpFile());
       ASSERT_TRUE(fp);
       ASSERT_EQ(j, fwrite(std::string(j, c).data(), 1, j, fp.get()));
       platform_handles->push_back(
@@ -195,7 +217,7 @@ TEST_F(PlatformChannelPairPosixTest, AppendReceivedFDs) {
   const std::string file_contents("hello world");
 
   {
-    base::ScopedFILE fp(tmpfile());
+    base::ScopedFILE fp(NewTmpFile());
     ASSERT_TRUE(fp);
     ASSERT_EQ(file_contents.size(),
               fwrite(file_contents.data(), 1, file_contents.size(), fp.get()));