Fix overloaded pipeline integration tests to support underflow.

Also disables the hash tests which seem to be flaking on the bots.
I was not able to reproduce this flake locally under valgrind.

BUG=492882, 496466
TEST=all pipeline tests pass under valgrind.

Review URL: https://codereview.chromium.org/1152803003

Cr-Commit-Position: refs/heads/master@{#333181}

media/test/pipeline_integration_test.cc

@@ -663,7 +663,9 @@ class PipelineIntegrationTest : public PipelineIntegrationTestHost {
         .Times(AtMost(1))
         .WillRepeatedly(SaveArg<0>(&metadata_));
     EXPECT_CALL(*this, OnBufferingStateChanged(BUFFERING_HAVE_ENOUGH))
-        .Times(AtMost(1));
+        .Times(AnyNumber());
+    EXPECT_CALL(*this, OnBufferingStateChanged(BUFFERING_HAVE_NOTHING))
+        .Times(AnyNumber());
 
     // Encrypted content not used, so this is never called.
     EXPECT_CALL(*this, OnWaitingForDecryptionKey()).Times(0);
@@ -700,7 +702,9 @@ class PipelineIntegrationTest : public PipelineIntegrationTestHost {
         .Times(AtMost(1))
         .WillRepeatedly(SaveArg<0>(&metadata_));
     EXPECT_CALL(*this, OnBufferingStateChanged(BUFFERING_HAVE_ENOUGH))
-        .Times(AtMost(1));
+        .Times(AnyNumber());
+    EXPECT_CALL(*this, OnBufferingStateChanged(BUFFERING_HAVE_NOTHING))
+        .Times(AnyNumber());
     EXPECT_CALL(*this, DecryptorAttached(true));
 
     // Encrypted content used but keys provided in advance, so this is

tools/valgrind/gtest_exclude/media_unittests.gtest.txt

@@ -5,6 +5,10 @@ FakeAudioInputTest.BasicCallbacks
 # Flaky under all Valgrind-based tools, see http://crbug.com/298771
 PipelineIntegrationTest.MediaSource_Opus_Seeking_WebM
 
+# Flaky under valgrind, http://crbug.com/492882
+PipelineIntegrationTest.BasicPlaybackHashed
+PipelineIntegrationTest.BasicPlaybackLive
+
 # crbug.com/409485, cannot revert due to git migration,
 # exclude the test now
 AudioInputTest.Record