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=olka@chromium.org

Bug: 1023677
Change-Id: I0c0ffb6f62ce9874799f0657a1e9585d1fbd648b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1957560
Auto-Submit: Ilia Samsonov <isamsonov@google.com>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722860}

media/base/audio_renderer_mixer_unittest.cc

@@ -526,7 +526,7 @@ TEST_P(AudioRendererMixerBehavioralTest, MixerPausesStream) {
 }
 
 INSTANTIATE_TEST_SUITE_P(
-    /* no prefix */,
+    All,
     AudioRendererMixerTest,
     testing::Values(
         // No resampling, 1 input sample rate.
@@ -560,7 +560,7 @@ INSTANTIATE_TEST_SUITE_P(
 // support single item lists and we don't want these test cases to run for every
 // parameter set.
 INSTANTIATE_TEST_SUITE_P(
-    /* no prefix */,
+    All,
     AudioRendererMixerBehavioralTest,
     testing::ValuesIn(std::vector<AudioRendererMixerTestData>(
         1,