Allows prefetch and other detachable requests to live beyond the renderer by delaying LinkLoader::Cancel requests by a few seconds and through the use of a new DetachedResourceHandler.

The general concept of a detachable resource should be useful for <a ping> as well.

BUG=286186

Review URL: https://codereview.chromium.org/25772002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231910 0039d316-1c4b-4281-b951-d872f2087c98
Remove Pickle::BeginWriteData/TrimWriteData, it's not used

BUG=None
R=jar@chromium.org

Review URL: https://codereview.chromium.org/38693003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231911 0039d316-1c4b-4281-b951-d872f2087c98
Port SincResampler's ConvolveBenchmark, as well as VectorMath's FMUL and FMAC benchmarks to media_perftests.

BUG=310837

Review URL: https://codereview.chromium.org/41633002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231912 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231910
[Android] Exclude test apks's from emma coverage.

BUG=None

Review URL: https://codereview.chromium.org/48363006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231913 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231912
SVN changes up to revision 231913