Estimate the renderer working set on Linux. This is less expensive and works in the Chromium SUID sandbox because it does not require access to /proc. Also cache the renderer memory usage value - in some workloads we ask for the memory usage too frequently.
Estimate the renderer working set on Linux. This is less expensive and works in the Chromium SUID sandbox because it does not require access to /proc. Also cache the renderer memory usage value - in some workloads we ask for the memory usage too frequently.

BUG=32519
TEST=none
Review URL: http://codereview.chromium.org/669105

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@40795 0039d316-1c4b-4281-b951-d872f2087c98

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