Revert of Track where WebContents are created in order to better understand issue. (patchset #2 id:20001 of https://codereview.chromium.org/1488883002/ )

Reason for revert:
This was meant to be a temporary patch so that we could get crash dumps. We now have these crash dumps.

Original issue's description:
> Track where WebContents are created in order to better understand issue.
>
> This is a temporary change to track down a beta blocking crash.
> This CL doesn't fix the crash, but will give us more information.
>
> The crash is happening when we attempt to show a modal dialog on some
> unknown WebContents that doesn't have a WebModalDialogManager. Not all
> WebContents are expecting to show modal dialogs and the creator of the
> WebModalDialog doesn't control what WebContents they will get at
> runtime. So, because of this loose coupling, we don't know which
> WebContents is triggering the crash.
>
> By adding this trace we expect to learn where the WebContents are
> created in order to make sure they have a WebModalDialogManager.
>
> BUG=538612
>
> Committed: https://crrev.com/a97dd34e9c8af59325e8478201487df0cac5c2af
> Cr-Commit-Position: refs/heads/master@{#363595}

[email protected],[email protected]
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=538612

Review URL: https://codereview.chromium.org/1525263002

Cr-Commit-Position: refs/heads/master@{#365299}
4 files changed