[chromedriver] Use 0 as the default value for deviceMetrics.width/height/pixelRatio.
[chromedriver] Use 0 as the default value for deviceMetrics.width/height/pixelRatio.

BUG=

Review URL: https://codereview.chromium.org/1377523006

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#352346}

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