Add prefix to empty param tests.

googletest will no longer support empty prefix
for parameterized INSTANTIATE_TEST_SUITE_P.
Adding "All" prefix to existing empty prefix test suites.

This CL was uploaded by git cl split.

R=mcasas@chromium.org

Bug: 1023677
Change-Id: I20f0bf799ee87047605bb384db6483025a817dd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1926863
Auto-Submit: Ilia Samsonov <isamsonov@google.com>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718630}

media/muxers/webm_muxer_unittest.cc

@@ -314,6 +314,6 @@ const TestParams kTestCases[] = {
     {kCodecVP8, kCodecPCM, 1, 1},
 };
 
-INSTANTIATE_TEST_SUITE_P(, WebmMuxerTest, ValuesIn(kTestCases));
+INSTANTIATE_TEST_SUITE_P(All, WebmMuxerTest, ValuesIn(kTestCases));
 
 }  // namespace media