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This CL adds a new dependency on the protocol buffer compiler
from the android source tree, since this compiler supports
generating Java files using the nano runtime.

The initial version of this dependency is 2.2.0a, but checked
out as what the Android 4.4.4 Release 2.0.1 tag points to.

This CL adds a new protoc binary (for compiling protos) that supports
this, and also adds a Java library with the runtime.

To simplify use of this, it also updates build/protoc_java.gypi to
support generating nano protos by specifying an optional
proto_runtime argument. The argument defaults to 'lite' which does
the same thing as before this change, and setting it to 'nano'
generates the new style Java files.

The plan is to quickly deprecate the 'lite' runtime for Java, since
it is too big and uses too many methods.

BUG=377891

Review URL: https://codereview.chromium.org/511283003

Cr-Commit-Position: refs/heads/master@{#292965}