Report Promise error-context strings to GA.

Report Promise error-context strings to GA.

Cleanup log record formatting (added missing spaces, remove redundant info).
Move machine id to from of log file names so they read better (really).

BUG=460614
TEST=None  // Well, you can start import, then yank the card to see if you can't force an error to happen, then check the network tab to see that a GA "exception" was sent with JUST the static error-context string from the related promise.

Review URL: https://codereview.chromium.org/953483003

Cr-Commit-Position: refs/heads/master@{#317833}
(cherry picked from commit 15a10b61c1b5e031e627803bd0580e85069da2d4)

Add support for log file rotation. Clean up error logging (more consistent formatting). Log stack traces. Ensure most substantial Promise chains used in importer code have catch clause hooked up to logger.

BUG=460614
BUG=449034
TEST=browser_test: FileManagerJsTest.*

Review URL: https://codereview.chromium.org/945933003

Cr-Commit-Position: refs/heads/master@{#317547}
(cherry picked from commit 4b600b552c6a611827539237270ce3f5eea17999)

TBR=mtomasz

Committed: https://chromium.googlesource.com/chromium/src/+/37cee9f563e15590eacea5723f78834d3f1aa04b

[Steve McKay, 2015-02-26 22:15:08]

smckay@chromium.org changed reviewers:
+ mtomasz@chromium.org

[Steve McKay, 2015-02-26 22:17:00]

Committed patchset #1 (id:1) manually as
37cee9f563e15590eacea5723f78834d3f1aa04b (presubmit successful).