Silence -Wtautological-compare-constant instance detected by clang

This 2016 code is passing a flag in place of a boolean value. The flag
happens to be non-zero (0 << 1), so this does not cause a behavior
change. All other tests pass true or false boolean literals, so this
does the same.

TBR=rockot@google.com

Bug: 1007367
Change-Id: Icd9a6fdb5b47a87d9dd19abdd8985323661f27b3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1822437Reviewed-by: Reid Kleckner <rnk@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Reid Kleckner <rnk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699419}

mojo/core/data_pipe_unittest.cc

@@ -1758,8 +1758,8 @@ TEST_F(DataPipeTest, Multiprocess) {
     // Send some data before serialising and sending the data pipe over.
     // This is the first write so we don't need to use WriteAllData.
     uint32_t num_bytes = kTestDataSize;
-    ASSERT_EQ(MOJO_RESULT_OK, WriteData(kMultiprocessTestData, &num_bytes,
-                                        MOJO_WRITE_DATA_FLAG_ALL_OR_NONE));
+    ASSERT_EQ(MOJO_RESULT_OK,
+              WriteData(kMultiprocessTestData, &num_bytes, true));
     ASSERT_EQ(kTestDataSize, num_bytes);
 
     // Send child process the data pipe.