[dom_distiller] Fix crash for invalid chrome-distiller:// requests

[dom_distiller] Fix crash for invalid chrome-distiller:// requests

When the DomDistillerViewerSource got a request for chrome-distiller://foobar/
it would crash if there was an empty path argument. This CL adds a safety check
for the length of the path, to ensure to not take a substring of an empty
string. 

In addition, this adds regression tests for the crash it fixes. It also fixes
the rest of the disabled browser tests for the DomDistillerViewerSource. 

BUG=356866
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=271178

[nyquist, 2014-05-16 07:07:33]

yfriedman: PTAL

[Yaron, 2014-05-16 17:07:42]

https://codereview.chromium.org/288353002/diff/100001/chrome/browser/dom_dist...
File chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc
(right):

https://codereview.chromium.org/288353002/diff/100001/chrome/browser/dom_dist...
chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc:110:
EXPECT_CALL(*distiller_page_factory_, CreateDistillerPageImpl())
I think this is needed even in the expect_distillation_ false case. At least for
test I added, I thought this ends up getting called manually. Did this break
other tests?

[nyquist, 2014-05-16 18:46:44]

yfriedman: PTAL

https://codereview.chromium.org/288353002/diff/100001/chrome/browser/dom_dist...
File chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc
(right):

https://codereview.chromium.org/288353002/diff/100001/chrome/browser/dom_dist...
chrome/browser/dom_distiller/dom_distiller_viewer_source_browsertest.cc:110:
EXPECT_CALL(*distiller_page_factory_, CreateDistillerPageImpl())
On 2014/05/16 17:07:42, Yaron wrote:
> I think this is needed even in the expect_distillation_ false case. At least
for
> test I added, I thought this ends up getting called manually. Did this break
> other tests?

Done.

[Yaron, 2014-05-16 19:46:58]

lgtm

[nyquist, 2014-05-16 19:57:06]

The CQ bit was checked by nyquist@chromium.org

[commit-bot: I haz the power, 2014-05-16 19:57:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/nyquist@chromium.org/288353002/120001

[commit-bot: I haz the power, 2014-05-16 21:16:57]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)

[commit-bot: I haz the power, 2014-05-17 04:11:38]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)

[commit-bot: I haz the power, 2014-05-17 05:30:07]

Change committed as 271178