Revert of Change CHECK into DCHECK. (patchset #1 id:1 of https://codereview.chromium.org/2721393002/ )

Reason for revert:
(per discussion, I was using this to get a signal. I'll send a cl to fix)

Original issue's description:
> Change CHECK into DCHECK.
>
> Code in the browser process should not be doing a CHECK based on data
> coming from the renderer process, as this allows a compromised renderer
> to trivially kill the whole browser.
>
> BUG=688425
> CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation
>
> Review-Url: https://codereview.chromium.org/2721393002
> Cr-Commit-Position: refs/heads/master@{#454047}
> Committed: https://chromium.googlesource.com/chromium/src/+/43f7ab4d121be7ad05f31728ccc130d500232031

TBR=creis@chromium.org,nasko@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=688425

Review-Url: https://codereview.chromium.org/2729613003
Cr-Commit-Position: refs/heads/master@{#454058}
diff --git a/content/browser/frame_host/navigation_controller_impl.cc b/content/browser/frame_host/navigation_controller_impl.cc
index bdb0c062..0995603 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -1213,7 +1213,7 @@
     // meanwhile and no new page was created. We are stuck at the last committed
     // entry.
     entry = GetLastCommittedEntry();
-    DCHECK(!is_in_page);
+    CHECK(!is_in_page);
     entry->GetSSL() = handle->ssl_status();
   } else if (params.nav_entry_id) {
     // This is a browser-initiated navigation (back/forward/reload).