Added a bitexactness test for the level estimator in the audio processing module

webrtc/modules/audio_processing/test/bitexactness_tools.h

Index: webrtc/modules/audio_processing/test/bitexactness_tools.h
diff --git a/webrtc/modules/audio_processing/test/bitexactness_tools.h b/webrtc/modules/audio_processing/test/bitexactness_tools.h
index 6a3309244735b7ea454ba32ff5bfd3f9448614b1..69f215577399982d4a25d3c9de51e5b03e76517f 100644
--- a/webrtc/modules/audio_processing/test/bitexactness_tools.h
+++ b/webrtc/modules/audio_processing/test/bitexactness_tools.h
@@ -19,6 +19,13 @@
 namespace webrtc {
 namespace test {
 
+// Gtest PRED_FORMAT test function that compares two integers
+// and reports any differences.
+::testing::AssertionResult AssertIntegersNotEqual(const char* m_expr,
+                                                  const char* n_expr,
+                                                  const int& output,
+                                                  const int& reference);
+
 // Gtest PRED_FORMAT test function that compares two floats
 // and reports any differences.
 ::testing::AssertionResult AssertFloatsNotEqual(const char* m_expr,