(Reland) Insert logcat as part of test result for android instrumentation tests.

In this cl, we are trying to add the logcat of each instrumentation
test into the corresponding test result object, so that when we are
checking the result of each test case, we would be able to see the
corresponding logcat for that test case at the same time.

The reason of reland is to fix the issue where environmental variables are not set.

BUG=631213

Review-Url: https://codereview.chromium.org/2545653002
Cr-Commit-Position: refs/heads/master@{#435550}
7 files changed