Fix a crash when download a DRM file through context menu

Fix a crash when download a DRM file through context menu

This is a regression introduced by
https://codereview.chromium.org/1717783002.
Previously we use URLUtil.guessFileName() to generate file names for
download.
However, to fix crbug/570750, we rely on the native code to pass the
file name.
However, drm download through context menu bypasses the native download
code.
As a result, we need to generate the file name in Java if it is null.
Since content disposition is null, this will not cause the same problem
as reported in crbug/570750.

BUG=608258
Committed: https://crrev.com/4e33c5d6978752f31ed6702e72e46fdf78cd5565
Cr-Commit-Position: refs/heads/master@{#395750}

[qinmin, 2016-05-24 22:26:26]

qinmin@chromium.org changed reviewers:
+ tedchoc@chromium.org

[qinmin, 2016-05-24 22:26:26]

PTAL

[Ted C, 2016-05-24 22:56:50]

lgtm

[qinmin, 2016-05-24 22:57:20]

The CQ bit was checked by qinmin@chromium.org

[commit-bot: I haz the power, 2016-05-24 22:57:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2013643002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/2013643002/1

[commit-bot: I haz the power, 2016-05-25 00:29:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-05-25 00:30:14]

Description was changed from

==========
Fix a crash when download a DRM file through context menu

This is a regression introduced by
https://codereview.chromium.org/1717783002.
Previously we use URLUtil.guessFileName() to generate file names for
download.
However, to fix crbug/570750, we rely on the native code to pass the
file name.
However, drm download through context menu bypasses the native download
code.
As a result, we need to generate the file name in Java if it is null.
Since content disposition is null, this will not cause the same problem
as reported in crbug/570750.

BUG=608258
==========

to

==========
Fix a crash when download a DRM file through context menu

This is a regression introduced by
https://codereview.chromium.org/1717783002.
Previously we use URLUtil.guessFileName() to generate file names for
download.
However, to fix crbug/570750, we rely on the native code to pass the
file name.
However, drm download through context menu bypasses the native download
code.
As a result, we need to generate the file name in Java if it is null.
Since content disposition is null, this will not cause the same problem
as reported in crbug/570750.

BUG=608258

Committed: https://crrev.com/4e33c5d6978752f31ed6702e72e46fdf78cd5565
Cr-Commit-Position: refs/heads/master@{#395750}
==========

[commit-bot: I haz the power, 2016-05-25 00:30:15]

Patchset 1 (id:??) landed as
https://crrev.com/4e33c5d6978752f31ed6702e72e46fdf78cd5565
Cr-Commit-Position: refs/heads/master@{#395750}