Convert content cache to use file paths

Convert content cache to use file paths

R=paulberry@google.com

Committed: https://code.google.com/p/dart/source/detail?r=44300

[Brian Wilkerson, 2015-03-06 17:10:02]

brianwilkerson@google.com changed reviewers:
+ paulberry@google.com

[Paul Berry, 2015-03-06 18:57:48]

lgtm.

How much more effort would it be to change the API of ContentCache to use String
rather than Source (in other words, make the client of ContentCache responsible
for converting from Source to fullpath rather than doing it inside
ContentCache).

The reason I'm suggesting this is that as the interface stands, a developer
unfamiliar with the history might easily assume that ContentCache still has the
old behavior.  If we changed the API to use file paths, that might eliminate a
lot of potential confusion.

[Brian Wilkerson, 2015-03-06 19:21:42]

> How much more effort would it be to change the API of ContentCache to use
String
> rather than Source ...

Not much coding effort, but my concern is that we would then be making the
analysis engine's API's inconsistent in that some API's use source and some a
file path. What I'd prefer to do (in a separate CL) is make the clean
distinction in the API that we talked about yesterday between Source and File.
The ContentCache API would then be re-written in terms of File rather than
Source, or worse yet a raw String.

[Brian Wilkerson, 2015-03-06 19:22:51]

Committed patchset #1 (id:1) manually as 44300 (presubmit successful).