Cleanup run-bindings-tests and use filecmp (23% faster r-b-t)

Cleanup run-bindings-tests and use filecmp (23% faster r-b-t)

The use of filecmp:
* speeds up r-b-t by 23% (if no diffs): (885 ms vs. 1.150 sec)
* uses only 1 process (if no diffs): 30 => 1
* if diffs, same speed
(can't measure difference, because filecmp is basically instantaneous on my machine)

Also some cleanup:
* remove dead code
* simplify temp file handling (caused build bot failures previously)
* don't catch exceptions, so easier to debug errors in CG
(because it's just one process now)

Currently r-b-t launches a separate diff(1) process for each file it compares.
Python has a built-in diff facility, which is extremely fast and avoids other processes.
This should make a big difference on Windows, meaning faster uploads for
Windows developers and less load on build bots.

Also a lot of the code is no longer necessary, after Terry's simplifications.
We can eliminate all the redundant temp file handling, and just need a simple
temp dir class.

R=haraken
BUG=341748
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=170315

[Nils Barth (inactive), 2014-03-28 10:03:06]

Quick cleanup, speedup, and robustness.

[haraken, 2014-03-28 10:33:18]

LGTM.

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
File Tools/Scripts/webkitpy/bindings/main.py (right):

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
Tools/Scripts/webkitpy/bindings/main.py:84: # contains unknown files (it isn't
aren't empty), hence use rmtree

isn't aren't => isn't

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
Tools/Scripts/webkitpy/bindings/main.py:97: # difflib is too slow, especially on
long output, so run diff

'difflib' and 'diff' are confusing. Shall we use 'diff command' and 'Python's
built-in diff'?

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
Tools/Scripts/webkitpy/bindings/main.py:105: return
self.executive.run_command(cmd, error_handler=lambda x: None)

Does this invoke Python's built-in diff?

[Nils Barth (inactive), 2014-03-28 10:47:25]

Revised, thanks!

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
File Tools/Scripts/webkitpy/bindings/main.py (right):

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
Tools/Scripts/webkitpy/bindings/main.py:84: # contains unknown files (it isn't
aren't empty), hence use rmtree
On 2014/03/28 10:33:18, haraken wrote:
> 
> isn't aren't => isn't

Done.

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
Tools/Scripts/webkitpy/bindings/main.py:97: # difflib is too slow, especially on
long output, so run diff
On 2014/03/28 10:33:18, haraken wrote:
> 
> 'difflib' and 'diff' are confusing. Shall we use 'diff command' and 'Python's
> built-in diff'?

Good point.
I've clarified the comment
(as "Python's difflib module" and "external diff(1) command")

https://codereview.chromium.org/216753002/diff/2/Tools/Scripts/webkitpy/bindi...
Tools/Scripts/webkitpy/bindings/main.py:105: return
self.executive.run_command(cmd, error_handler=lambda x: None)
On 2014/03/28 10:33:18, haraken wrote:
> Does this invoke Python's built-in diff?

No, it invokes an external command.
Python's built-in diff is the difflib module.
I've clarified comments.

[Nils Barth (inactive), 2014-03-28 10:47:44]

The CQ bit was checked by nbarth@chromium.org

[commit-bot: I haz the power, 2014-03-28 10:47:46]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/nbarth@chromium.org/216753002/90001

[commit-bot: I haz the power, 2014-03-28 11:47:24]

Change committed as 170315