Code:  TaskService::TaskService()
    : next_instance_id_(0), bound_instance_id_(kInvalidInstanceId) {}

Vulnerability Type: DoS 
CWE ID: CWE-20
Summary: The LoadIC::UpdateCaches function in ic/ic.cc in Google V8, as used in Google Chrome before 48.0.2564.82, does not ensure receiver compatibility before performing a cast of an unspecified variable, which allows remote attackers to cause a denial of service or possibly have unknown other impact via crafted JavaScript code.
Commit Message: Change ReadWriteLock to Lock+ConditionVariable in TaskService

There are non-trivial performance implications of using shared
SRWLocking on Windows as more state has to be checked.

Since there are only two uses of the ReadWriteLock in Chromium after
over 1 year, the decision is to remove it.

BUG=758721

Change-Id: I84d1987d7b624a89e896eb37184ee50845c39d80
Reviewed-on: https://chromium-review.googlesource.com/634423
Commit-Queue: Robert Liao <robliao@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Francois Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#497632}