Revert "Disable legacy hooking in the browser process"

This reverts commit 0b9afd3b.

Reason for revert: This CL changed the behavior of IMEs by
launching them in TF_TMF_IMMERSIVEMODE

Original change's description:
> Disable legacy hooking in the browser process
>
> Now that TSF is enabled by default in m75, there are no
> known blocking issue anymore.
>
> Bug: 557798
> Change-Id: Iaf060e267982d3f90acc5281caf99ff02e155dbd
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1597282
> Reviewed-by: Will Harris <wfh@chromium.org>
> Commit-Queue: Patrick Monette <pmonette@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#657798}

TBR=pmonette@chromium.org,wfh@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 557798, 962310
Change-Id: I58fc91b39077520afcb5f39d3d881c72ecac2bbf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610089
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Reviewed-by: Patrick Monette <pmonette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659197}

chrome/chrome_elf/chrome_elf_main.cc

@@ -8,7 +8,6 @@
 #include <windows.h>
 
 #include "chrome/chrome_elf/blacklist/blacklist.h"
-#include "chrome/chrome_elf/chrome_elf_security.h"
 #include "chrome/chrome_elf/crash/crash_helper.h"
 #include "chrome/chrome_elf/third_party_dlls/main.h"
 #include "chrome/install_static/install_details.h"
@@ -71,9 +70,6 @@ BOOL APIENTRY DllMain(HMODULE module, DWORD reason, LPVOID reserved) {
     if (install_static::IsNonBrowserProcess())
       return TRUE;
 
-    // Disable legacy hooking.
-    elf_security::EarlyBrowserSecurity();
-
     __try {
       // Initialize blacklist before initializing third_party_dlls.
       // Note: "blacklist" is deprecated in favor of "third_party_dlls", but