[Merge M52] Use correct origin when prompting for proxy authentication.

[Merge M52] Use correct origin when prompting for proxy authentication.

Since M49, Chrome has been prompting for proxy authentication
credentials using the target origin instead of the origin of the proxy
server. Even if the proxy origin was displayed correctly, a mischievous
network operator could still spoof the proxy server origin. To mitigate
these problems, this CL:

* Fixes the origin used in the proxy authentication login prompt to use
  the origin of the proxy server.

* Indicate if the proxy server connection is insecure.

* Always throw up an interstitial and clear the omnibox when showing a
  proxy auth prompt.

* Use the correct origin when saving proxy authentication credentials.

BUG=613626, 620737
Review-Url: https://codereview.chromium.org/2067933002
Cr-Commit-Position: refs/heads/master@{#400247}
(cherry picked from commit 098c009df7a4ddc5c23d4d3c9dccf5eff1f24c98)

Committed: https://chromium.googlesource.com/chromium/src/+/8c8b7cc66aa395a12b7a25f59d9cd4d1eb71f1a4

[asanka, 2016-06-20 14:56:47]

Description was changed from

==========
[Merge M52] Use correct origin when prompting for proxy authentication.

Since M49, Chrome has been prompting for proxy authentication
credentials using the target origin instead of the origin of the proxy
server. Even if the proxy origin was displayed correctly, a mischievous
network operator could still spoof the proxy server origin. To mitigate
these problems, this CL:

* Fixes the origin used in the proxy authentication login prompt to use
  the origin of the proxy server.

* Indicate if the proxy server connection is insecure.

* Always throw up an interstitial and clear the omnibox when showing a
  proxy auth prompt.

* Use the correct origin when saving proxy authentication credentials.

BUG=613626, 620737

Review-Url: https://codereview.chromium.org/2067933002
Cr-Commit-Position: refs/heads/master@{#400247}
(cherry picked from commit 098c009df7a4ddc5c23d4d3c9dccf5eff1f24c98)
==========

to

==========
[Merge M52] Use correct origin when prompting for proxy authentication.

Since M49, Chrome has been prompting for proxy authentication
credentials using the target origin instead of the origin of the proxy
server. Even if the proxy origin was displayed correctly, a mischievous
network operator could still spoof the proxy server origin. To mitigate
these problems, this CL:

* Fixes the origin used in the proxy authentication login prompt to use
  the origin of the proxy server.

* Indicate if the proxy server connection is insecure.

* Always throw up an interstitial and clear the omnibox when showing a
  proxy auth prompt.

* Use the correct origin when saving proxy authentication credentials.

BUG=613626, 620737

Review-Url: https://codereview.chromium.org/2067933002
Cr-Commit-Position: refs/heads/master@{#400247}
(cherry picked from commit 098c009df7a4ddc5c23d4d3c9dccf5eff1f24c98)

Committed:
https://chromium.googlesource.com/chromium/src/+/8c8b7cc66aa395a12b7a25f59d9c...
==========

[asanka, 2016-06-20 14:56:48]

Committed patchset #1 (id:1) manually as
8c8b7cc66aa395a12b7a25f59d9cd4d1eb71f1a4.