Revert "Ice Server API integration"

This reverts commit b23ba4d3fb.

Reason for revert: Speculative revert for multiple failures in https://ci.chromium.org/p/chrome/builders/ci/linux-chromeos-chrome/2057

Original change's description:
> Ice Server API integration
> 
> Integrates network traversal API to fetch stun and turn servers for
> webrtc p2p connection. Handles API failure by returning a list of
> public Google stun servers as a fallback.
> 
> Bug: 1031156
> Change-Id: I60b5d6ccdb749ce9375bcb3333dc2cbdab62aa18
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1994295
> Commit-Queue: Himanshu Jaju <himanshujaju@chromium.org>
> Reviewed-by: Martin Šrámek <msramek@chromium.org>
> Reviewed-by: David Roger <droger@chromium.org>
> Reviewed-by: Richard Knoll <knollr@chromium.org>
> Reviewed-by: Alex Gough <ajgo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#733941}

TBR=droger@chromium.org,msramek@chromium.org,knollr@chromium.org,himanshujaju@chromium.org,ajgo@chromium.org

Change-Id: I62270288afa5716c4dfb5fa6c35df2cfe0a82d79
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1031156
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013288
Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733995}

google_apis/google_api_keys.h

@@ -76,9 +76,6 @@ std::string GetNonStableAPIKey();
 // Retrieves the Chrome Remote Desktop API key.
 std::string GetRemotingAPIKey();
 
-// Retrieves the Sharing API Key.
-std::string GetSharingAPIKey();
-
 #if defined(OS_IOS)
 // Sets the API key. This should be called as early as possible before this
 // API key is even accessed.