Add a DCHECK_CURRENTLY_ON(BrowserThread::ID) macro.

I've often lost time when a DCHECK(BrowserThread::CurrentlyOn(id)) fails,
because I needed to re-run the program in gdb to figure out which thread was
actually running the function. This new wrapper macro should make that clearer.

I've converted one file in service_worker to make sure everything works.
It changes:

[...:FATAL:service_worker_context_core.cc(75)] Check failed: BrowserThread::CurrentlyOn(BrowserThread::IO).

into

[...:FATAL:service_worker_context_core.cc(75)] Check failed: ::content::BrowserThread::CurrentlyOn(BrowserThread::IO). Must be called on Chrome_IOThread; actually called on Chrome_UIThread.

Review URL: https://codereview.chromium.org/191763002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256913 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256913
Do not forge response headers text for SPDY requests.

BUG=350113

Review URL: https://codereview.chromium.org/198193003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256914 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256914