The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6a7e84782f979dd2720761025881ac62ddf41b1c

commit 6a7e84782f979dd2720761025881ac62ddf41b1c
Author: hongchan <hongchan@chromium.org>
Date: Thu Aug 25 19:13:42 2016

Remove redundant definition of Spatializer abstract class

platform/audio/Spatializer.h. was originally designed to own various type of
panners including equal power, HRTF, stereo, sound-field and more.
However, the direction has been changed and now it is reasonable to remove
Spatializer class and make the StereoPanner standalone.

BUG= 612299 
TEST=NONE (the CL build passes all the panner-related tests.)

Review-Url: https://codereview.chromium.org/2272683003
Cr-Commit-Position: refs/heads/master@{#414502}

[modify] https://crrev.com/6a7e84782f979dd2720761025881ac62ddf41b1c/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.cpp
[modify] https://crrev.com/6a7e84782f979dd2720761025881ac62ddf41b1c/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.h
[delete] https://crrev.com/cc77d07303f42212610e01d7fac2e8e4dd01647a/third_party/WebKit/Source/platform/audio/Spatializer.cpp
[delete] https://crrev.com/cc77d07303f42212610e01d7fac2e8e4dd01647a/third_party/WebKit/Source/platform/audio/Spatializer.h
[modify] https://crrev.com/6a7e84782f979dd2720761025881ac62ddf41b1c/third_party/WebKit/Source/platform/audio/StereoPanner.cpp
[modify] https://crrev.com/6a7e84782f979dd2720761025881ac62ddf41b1c/third_party/WebKit/Source/platform/audio/StereoPanner.h
[modify] https://crrev.com/6a7e84782f979dd2720761025881ac62ddf41b1c/third_party/WebKit/Source/platform/blink_platform.gypi