Revert of Loosening the coupling between WebRTC and //third_party/protobuf

Revert of Loosening the coupling between WebRTC and //third_party/protobuf (patchset #16 id:300001 of https://codereview.webrtc.org/2747863003/ )

Reason for revert:
I will try to reland next week because it is causing some problems.

Original issue's description:
> To accommodate some downstream WebRTC users we need to loosen
> the coupling between our code and the //third_party/protobuf.
> 
> This includes using typedefs to define strings instead of
> assuming std::string.
> 
> After this refactoring it will be possible to link with other
> protobuf implementations than the current one.
> 
> We moved the PRESUBMIT check to another CL [1]. The goal of this
> presubmit is to avoid the direct usage of google::protobuf outside
> of the webrtc/base/protobuf_utils.h header file.
> 
> [1] - https://codereview.webrtc.org/2753823003/
> 
> BUG=webrtc:7340
> NOTRY=True
> 
> Review-Url: https://codereview.webrtc.org/2747863003
> Cr-Commit-Position: refs/heads/master@{#17466}
> Committed: https://chromium.googlesource.com/external/webrtc/+/16ab93b952f9e8268f2e663ffe49548e8043d5af

TBR=kjellander@webrtc.org,henrik.lundin@webrtc.org,kwiberg@webrtc.org,michaelt@webrtc.org,peah@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7340
Review-Url: https://codereview.webrtc.org/2786363002
Cr-Commit-Position: refs/heads/master@{#17483}
Committed: https://chromium.googlesource.com/external/webrtc/+/d00aad5eb2fa5a7b5aeda714f7702b50cd26ee28

[mbonadei, 2017-03-31 09:43:02]

The CQ bit was checked by mbonadei@webrtc.org

[mbonadei, 2017-03-31 09:43:02]

Created Revert of Loosening the coupling between WebRTC and
//third_party/protobuf

[commit-bot: I haz the power, 2017-03-31 09:43:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2017-03-31 10:08:08]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490953382478690, "parent_rev":
"124a6fcddfdf80112b7c7687d657d2fb36c9b6e7", "commit_rev":
"d00aad5eb2fa5a7b5aeda714f7702b50cd26ee28"}

[commit-bot: I haz the power, 2017-03-31 10:08:10]

Description was changed from

==========
Revert of Loosening the coupling between WebRTC and //third_party/protobuf
(patchset #16 id:300001 of https://codereview.webrtc.org/2747863003/ )

Reason for revert:
I will try to reland next week because it is causing some problems.

Original issue's description:
> To accommodate some downstream WebRTC users we need to loosen
> the coupling between our code and the //third_party/protobuf.
> 
> This includes using typedefs to define strings instead of
> assuming std::string.
> 
> After this refactoring it will be possible to link with other
> protobuf implementations than the current one.
> 
> We moved the PRESUBMIT check to another CL [1]. The goal of this
> presubmit is to avoid the direct usage of google::protobuf outside
> of the webrtc/base/protobuf_utils.h header file.
> 
> [1] - https://codereview.webrtc.org/2753823003/
> 
> BUG=webrtc:7340
> NOTRY=True
> 
> Review-Url: https://codereview.webrtc.org/2747863003
> Cr-Commit-Position: refs/heads/master@{#17466}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/16ab93b952f9e8268f2e663ff...

TBR=kjellander@webrtc.org,henrik.lundin@webrtc.org,kwiberg@webrtc.org,michael...
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7340
==========

to

==========
Revert of Loosening the coupling between WebRTC and //third_party/protobuf
(patchset #16 id:300001 of https://codereview.webrtc.org/2747863003/ )

Reason for revert:
I will try to reland next week because it is causing some problems.

Original issue's description:
> To accommodate some downstream WebRTC users we need to loosen
> the coupling between our code and the //third_party/protobuf.
> 
> This includes using typedefs to define strings instead of
> assuming std::string.
> 
> After this refactoring it will be possible to link with other
> protobuf implementations than the current one.
> 
> We moved the PRESUBMIT check to another CL [1]. The goal of this
> presubmit is to avoid the direct usage of google::protobuf outside
> of the webrtc/base/protobuf_utils.h header file.
> 
> [1] - https://codereview.webrtc.org/2753823003/
> 
> BUG=webrtc:7340
> NOTRY=True
> 
> Review-Url: https://codereview.webrtc.org/2747863003
> Cr-Commit-Position: refs/heads/master@{#17466}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/16ab93b952f9e8268f2e663ff...

TBR=kjellander@webrtc.org,henrik.lundin@webrtc.org,kwiberg@webrtc.org,michael...
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7340

Review-Url: https://codereview.webrtc.org/2786363002
Cr-Commit-Position: refs/heads/master@{#17483}
Committed:
https://chromium.googlesource.com/external/webrtc/+/d00aad5eb2fa5a7b5aeda714f...
==========

[commit-bot: I haz the power, 2017-03-31 10:08:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/d00aad5eb2fa5a7b5aeda714f...

[mbonadei, 2017-04-03 18:30:40]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.webrtc.org/2791963003/ by mbonadei@webrtc.org.

The reason for reverting is: Trying to re-land after solving some related
issues..