Reduce cpu usage -- don't render earth if page is not visible
BUG=none
TEST=manual
R=binji@chromium.org, eliben@chromium.org

Review URL: https://codereview.chromium.org/25428006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226891 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226891
Add NavigationMetricsRecorder to Android.

BUG=299172
TEST=Navigation.MainFrameScheme appears in about:histograms in Android

Review URL: https://codereview.chromium.org/25088003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226892 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226892