DevTools: CPU throttling should disable when DevTools are closed.

BUG=654138

Review-Url: https://codereview.chromium.org/2399883005
Cr-Commit-Position: refs/heads/master@{#424042}
(cherry picked from commit 94eb2d6a00a578b21a22f5c8cc9e5661d29b2a9e)

Review URL: https://codereview.chromium.org/2407973002 .

Cr-Commit-Position: refs/branch-heads/2840@{#706}
Cr-Branched-From: 1ae106dbab4bddd85132d5b75c670794311f4c57-refs/heads/master@{#414607}
1 file changed