Revert "Add SODA API Key"

This reverts commit b01fb51632.

Reason for revert: causes crashes on chrome-branded CrOS builds
See crbug.com/1108123#c2 for details.

Original change's description:
> Add SODA API Key
> 
> This CL adds an API key for the Speech On-Device API (SODA). Usage of
> the API key is outlined here: go/securing-soda-on-chrome.
> 
> Bug: 1107615
> Change-Id: Ic92418407e17a88426559251e77797bd0b34818b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2309133
> Reviewed-by: David Roger <droger@chromium.org>
> Commit-Queue: Evan Liu <evliu@google.com>
> Cr-Commit-Position: refs/heads/master@{#790550}

TBR=droger@chromium.org,evliu@google.com

Change-Id: I64f9e46714ca6675e74702dc1d1a446d873ed741
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1107615, 1108123
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2311077
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790686}

google_apis/google_api_keys.h

@@ -80,9 +80,6 @@ std::string GetRemotingAPIKey();
 // Retrieves the Sharing API Key.
 std::string GetSharingAPIKey();
 
-// Retrieves the Speech On-Device API (SODA) API Key.
-std::string GetSodaAPIKey();
-
 #if defined(OS_IOS)
 // Sets the API key. This should be called as early as possible before this
 // API key is even accessed.