[SyncFS] Remove friend classes of MetadataDatabase

* Move CreateForTesting to public.
* Drop friend specifier for test classes.

BUG=344769
NOTRY=true

Review URL: https://codereview.chromium.org/182513004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254075 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254075
Update the 'Learn More' link on the malware interstitial

Currently the 'learn more' link points to the safety center, which is generic and says nothing about malware or phishing. Updated to point to the Safe Browsing Transparency Report, which mentions both phishing and malware.

BUG=346118
R=mattm@chromium.org

Review URL: https://codereview.chromium.org/176703002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254076 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254076