Invoke the geolocation callback only if there is pending request.
Invoke the geolocation callback only if there is pending request.

BUG=511338
TBR=boliu

Review URL: https://codereview.chromium.org/1248803004

Cr-Commit-Position: refs/heads/master@{#340194}
(cherry picked from commit 2b11e017ff2c8d4ec5322b7cdbf477b1b32a9c17)

Review URL: https://codereview.chromium.org/1262453002 .

Cr-Commit-Position: 62bea078bfe806fd4d8dc2d3869914b6c8093498@{#153}
Cr-Branched-From: ef8f355264e75087b06072b03d328c50bf72843a@{#338390}

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