Tracking merge of dalvik-dev to master

Adapt to change in the way MockWebServer sets up CONNECT proxies.
  git cherry-pick --no-commit c7e2feee5e7908a019a0de91123c1feb9bdc38bc

React to move of Base64 in libcore
  git cherry-pick --no-commit 119f7ebdd1f8df3a8ff8e3b8056bff725d569253

Expose and document android.net.HttpResponseCache.
  git cherry-pick --no-commit 7b73f0fdb8c032a65c55610541d66385bd8bcbe6)

make update-api

Change-Id: Ieb48b304ea38ee8c2ec01e860d99b1404583889e