Add a "Learn more" link in the "Sign in with a different account" confirmation dialog.

Add a "Learn more" link to a troubleshooting page at the bottom of the "Sign in with a different account" dialog.

Expected result:
http://i.imgur.com/txdpn4R.png (Mac)
http://i.imgur.com/QvIfDr4.png (Windows)

TEST=
1. Sign in to Chrome with a first account (hot-dog menu > Sign in to Chrome...).
2. Sign out (hot-dog menu > Settings > Disconnect your Google Account...).
3. Sign in to Chrome with a different account than the one used at step 1.
Expected result: In the "Sign in with a different account" confirmation dialog that appears, there should be a "Learn more" link.
4. Click on the "Learn more" link.
Expected result: A help page is loaded in a popup.
BUG=268379

Review URL: https://codereview.chromium.org/22165004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227174 0039d316-1c4b-4281-b951-d872f2087c98
Added WebCypto digest OpenSSL implementation.

BUG=267888
TEST=content_unittests --gtest_filter="WebCryptoImpl*"

Review URL: https://codereview.chromium.org/23621050

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227175 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227175
Fix range requests on Telemetry http server.

Per protocol http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html a byte range request of 'bytes=START_BYTE-' should return bytes starting at START_BYTE till end of file.

BUG=278611

Review URL: https://codereview.chromium.org/24293003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227176 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227176