Revert 116191 - Input latency performance test that uses tracing.

Revert 116191 - Input latency performance test that uses tracing.

This CL adds a new gyp target called performance_browser_tests to run the new input latency test as a browser test.

See the comments in latency_tests.cc for an overview of how latency is measured.

Review URL: http://codereview.chromium.org/8883005

TBR=jbates@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=116202