Make LogMessage() handle strings with null bytes

'LOG(...) << std::string("a\0a", 3);' would cause the line to be
truncated, and no newline output.

Review URL: https://codereview.chromium.org/198103008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257093 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 257093
Expose size() and isEmpty() in ObserverList.

BUG=347558

Review URL: https://codereview.chromium.org/198093004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257094 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 257094