CDM_8 usage is very low now. It seems it's time to remove it in M-68.

I'll start working on this to clean things up a bit before we stabilize CDM_10 interface.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/cdm/+/1610b3d3c98e09de2e09b968821cddb10014c683

commit 1610b3d3c98e09de2e09b968821cddb10014c683
Author: Xiaohan Wang <xhwang@chromium.org>
Date: Tue Apr 17 20:59:44 2018

cdm: Remove ContentDecryptionModule_8 interface

ContentDecryptionModule_9 CDM has been shipped in Chromium 64 and
above. We do not need the support of ContentDecryptionModule_8 any
more.

Bug:  737296 
Change-Id: I658d0306a8431078ea235bbae79e0a285cfcbc78
Reviewed-on: https://chromium-review.googlesource.com/1015622
Reviewed-by: Rintaro Kuroiwa <rkuroiwa@chromium.org>

[modify] https://crrev.com/1610b3d3c98e09de2e09b968821cddb10014c683/content_decryption_module.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/cdm/+/57e20546bc2afeabae7716ae3fc73bf091a76343

commit 57e20546bc2afeabae7716ae3fc73bf091a76343
Author: Xiaohan Wang <xhwang@chromium.org>
Date: Tue Apr 17 21:56:53 2018

cdm: Misc cleanup in content_decryption_module.h

- Move common data types to the beginning of the file. Previously they
  are scattered in three groups, making it harder to read.
- Remove unnecessary forward declarations after the move.

Bug:  737296 
Change-Id: Iead8a468f9fa23b8f014bacca7105784b78c7fa3
Reviewed-on: https://chromium-review.googlesource.com/1015656
Reviewed-by: Haoming Chen <hmchen@chromium.org>

[modify] https://crrev.com/57e20546bc2afeabae7716ae3fc73bf091a76343/content_decryption_module.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/778e8cf0c8041398b4fb763c0d5a054b42797ce8

commit 778e8cf0c8041398b4fb763c0d5a054b42797ce8
Author: Xiaohan Wang <xhwang@chromium.org>
Date: Tue Apr 17 22:09:23 2018

media: Remove cdm::ContentDecryptionModule_8 support

CDM_9 support has been shipped in Chomium for multiple releases. All new CDMs
should use CDM_9 and above. Hence removing support for CDM_8.

only cover CDM_9 and CDM_10.

Bug:  737296 
Test: Removing support of old interface support. Currently our tests
Change-Id: I22facd6dc6e18933a295d3aece7ba2de1369cb79
Reviewed-on: https://chromium-review.googlesource.com/1015640
Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551494}
[modify] https://crrev.com/778e8cf0c8041398b4fb763c0d5a054b42797ce8/media/cdm/cdm_adapter.cc
[modify] https://crrev.com/778e8cf0c8041398b4fb763c0d5a054b42797ce8/media/cdm/cdm_adapter.h
[modify] https://crrev.com/778e8cf0c8041398b4fb763c0d5a054b42797ce8/media/cdm/cdm_wrapper.h
[modify] https://crrev.com/778e8cf0c8041398b4fb763c0d5a054b42797ce8/media/cdm/supported_cdm_versions.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aa45b569402d11ac7bce59eddde46288b13077a0

commit aa45b569402d11ac7bce59eddde46288b13077a0
Author: Xiaohan Wang <xhwang@chromium.org>
Date: Wed Apr 18 03:46:59 2018

Roll src/media/cdm/api/ cc347b850..57e20546b (3 commits)

https://chromium.googlesource.com/chromium/cdm.git/+log/cc347b850c11..57e20546bc2a

$ git log cc347b850..57e20546b --date=short --no-merges --format='%ad %ae %s'
2018-04-17 xhwang cdm: Misc cleanup in content_decryption_module.h
2018-04-17 xhwang cdm: Remove ContentDecryptionModule_8 interface
2018-04-09 hmchen Fix the invalid URL of InitDataType

Created with:
  roll-dep src/media/cdm/api

Bug:  737296 
Change-Id: Icab2f50843948c52cd0e4a275afcfad4c8f33114
Reviewed-on: https://chromium-review.googlesource.com/1015848
Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551571}
[modify] https://crrev.com/aa45b569402d11ac7bce59eddde46288b13077a0/DEPS