Revert "Add a NOTREACHED and uma stat when the audio callback fails."

This reverts commit 07a90a91.

Revert "Fixes bug in Media.AudioInputCbErrorMac histogram."

This reverts commit beaa161b.

Rationale: appears to make AppRTC hang on Mac. This looks like the
only related CL in the blamelist, speculatively reverting.

BUG=428706
TBR=xians@chromium.org

Review URL: https://codereview.chromium.org/695393002

Cr-Commit-Position: refs/heads/master@{#302491}

media/audio/mac/audio_low_latency_input_mac.cc

@@ -9,7 +9,6 @@
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/mac/mac_logging.h"
-#include "base/metrics/sparse_histogram.h"
 #include "media/audio/mac/audio_manager_mac.h"
 #include "media/base/audio_bus.h"
 #include "media/base/data_buffer.h"
@@ -497,11 +496,8 @@ OSStatus AUAudioInputStream::InputProc(void* user_data,
                                     bus_number,
                                     number_of_frames,
                                     audio_input->audio_buffer_list());
-  if (result) {
-    UMA_HISTOGRAM_SPARSE_SLOWLY("Media.AudioInputCbErrorMac", result);
-    NOTREACHED();
+  if (result)
     return result;
-  }
 
   // Deliver recorded data to the consumer as a callback.
   return audio_input->Provide(number_of_frames,

tools/metrics/histograms/histograms.xml

@@ -11721,13 +11721,6 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <summary>Audio codec used in HTML5 media.</summary>
 </histogram>
 
-<histogram name="Media.AudioInputCbErrorMac" units="OSStatus">
-  <owner>xians@chromium.org</owner>
-  <summary>
-    Error codes that AudioUnitRender() returns in AUAudioInputStream on Mac.
-  </summary>
-</histogram>
-
 <histogram name="Media.AudioInputController" units="ms">
   <owner>dalecurtis@chromium.org</owner>
   <summary>Measures the time taken for AudioInputController::</summary>