Revert of [Suggestions] Move ImageManager to the component (patchset …

…#6 id:220001 of https://codereview.chromium.org/543753002/)

Reason for revert:
One of the new unit tests failed with uninit memory access: http://build.chromium.org/p/chromium.memory.fyi/builders/Chromium%20OS%20%28valgrind%29%282%29/builds/43137/

Original issue's description:
> [Suggestions] Move ImageManager to the component
>
> Keeps the fetcher functionality as ImageFetcherImpl in chrome/browser/search/suggestions.
>
> BUG=387751
> TBR=blundell
> TEST=ImageManagerTest,ImageFetcherBrowserTest
>
> Committed: https://crrev.com/5a25f30080dd57d200679546c970d70f2247def9
> Cr-Commit-Position: refs/heads/master@{#296503}

TBR=huangs@chromium.org,blundell@chromium.org,mathp@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=387751

Review URL: https://codereview.chromium.org/600203002

Cr-Commit-Position: refs/heads/master@{#296553}