Add flag for verbose build of instrumented libraries

BUG=313751
R=glider@chromium.org,earthdok@chromium.org
TBR=cpu@chromium.org

Review URL: https://codereview.chromium.org/104273002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238702 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238702
Make MIDIManager::DispatchSendMIDIData pure virtual.

With this CL, each OS-specific implementation of MIDIManager is responsible for implementing DispatchSendMIDIData() as a non-blocking function.

Main motivations of this change are:
- Whether non-blocking implementation of DispatchSendMIDIData() requires a background thread or not depends on MIDI APIs on each platform.
- If the base class owns a background thread and the actual dispatch method is overridden by each implementation class, such background thread must be terminated *before* the subclass destructor() is finished to avoid pure virtual function call. This is a trick requirement in resource cleanup order that we'd like to avoid.

BUG=303599
TEST=manually done on Mac

Review URL: https://codereview.chromium.org/97583002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238703 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238703