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1. Automate the selection of the proper channel to enable the verifier.
   Now the code is enabled at runtime.

2. Switch to a hash_map to track handles.

3. Intercept CloseHandle to detect the code that is closing handles owned
   by ScopedHandles. The initial implementation only covers chrome.exe/dll,
   but the plan is to extend that in the future to all modules loaded in the
   process.

BUG=362176
R=cpu@chromium.org
R=sky@chromium.org

See https://codereview.chromium.org/490043002/ for the actual review.

TBR=cpu@chromium.org
TBR=sky@chromium.org

Review URL: https://codereview.chromium.org/506013004

Cr-Commit-Position: refs/heads/master@{#291969}