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Mostly just a refactoring of build rules to support prebuilt jars.

Adds support for proguard preprocessing of both prebuilt and
non-prebuilt java libraries.

Adds definitions of all (but for android.jar) of the prebuilt jars that
we need from the sdk.

BUG=359249

Review URL: https://codereview.chromium.org/484813002

Cr-Commit-Position: refs/heads/master@{#291464}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291464 0039d316-1c4b-4281-b951-d872f2087c98