Ensure callbacks are reset when disconnecting a TCPSocket/UDPSocket.

BUG=251977

Review URL: https://codereview.chromium.org/29523003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229953 0039d316-1c4b-4281-b951-d872f2087c98
Rename BeginFrame to BeginMainFrame and BeginImplFrame in cc::Scheduler.

Second patch in a series to rename BeginFrame. This patch focuses on
cc::Scheduler.

In the scheduler, the term 'BeginFrame' is used for both the main thread and the
impl thread. This can cause confusion if it's not obvious which one is being
refered to. To clarify this, we rename BeginFrame to BeginMainFrame and
BeginImplFrame, respectively.

BUG=261765

Review URL: https://codereview.chromium.org/32343002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229954 0039d316-1c4b-4281-b951-d872f2087c98
Add comment about "Confidence in Bisection Results" and "Author" output. The perf dashboard looks for these strings, so warn anybody about changing them.

BUG=
NOTRY=true

Review URL: https://codereview.chromium.org/33833002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229955 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229954
SVN changes up to revision 229955