Do not migrate NetworkPrediction preference on Android.
Do not migrate NetworkPrediction preference on Android.

Do not call chrome_browser_net::MigrateNetworkPredictionUserPrefs() on Android,
because preference migration from kNetworkPredictionEnabled to
kNetworkPredictionOptions is carried out by some platform-specific code on
Android.

BUG=334602

Review URL: https://codereview.chromium.org/456813002

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@288714 0039d316-1c4b-4281-b951-d872f2087c98

littlstar/chromium.src,ondra-novak/chromium.src,ondra-novak/chromium.src,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,bright-sparks/chromium-spacewalk,littlstar/chromium.src,ondra-novak/chromium.src,ondra-novak/chromium.src,ondra-novak/chromium.src,littlstar/chromium.src,littlstar/chromium.src,littlstar/chromium.src,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,ondra-novak/chromium.src,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,littlstar/chromium.src,littlstar/chromium.src,littlstar/chromium.src,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk