Add timer histogram for egl::Initialize time.
Add timer histogram for egl::Initialize time.

This can help is track startup time regressions within ANGLE.

BUG=436191
BUG=angleproject:944

Change-Id: I73cf2449661b909dced4ddc11957037ed5535fc0
Reviewed-on: https://chromium-review.googlesource.com/272613
Reviewed-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>
Reviewed-by: Brandon Jones <303ddc8529a3012e7fb187d611f08537af0cc183@chromium.org>
Tested-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>

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