Fix for issue 10488 standalone/basic_debugger_test flaky

Fix for issue 10488 standalone/basic_debugger_test flaky

R=hausner@google.com

Committed: https://code.google.com/p/dart/source/detail?r=22531

[hausner, 2013-05-08 15:26:48]

Thank you for fixing this. LGTM with one comment.

https://codereview.chromium.org/15051002/diff/1/runtime/bin/dbg_connection.cc
File runtime/bin/dbg_connection.cc (right):

https://codereview.chromium.org/15051002/diff/1/runtime/bin/dbg_connection.cc...
runtime/bin/dbg_connection.cc:283: handler_lock_ = new dart::Monitor();
What if two threads call this function by accident? Then there will be two
locks, and one thread may have lock 1 while the second one grabs lock 2.

Not entirely safe, but maybe good enough: ASSERT(handler_lock_ == NULL) before
allocating the lock.

[siva, 2013-05-08 20:48:12]

https://codereview.chromium.org/15051002/diff/1/runtime/bin/dbg_connection.cc
File runtime/bin/dbg_connection.cc (right):

https://codereview.chromium.org/15051002/diff/1/runtime/bin/dbg_connection.cc...
runtime/bin/dbg_connection.cc:283: handler_lock_ = new dart::Monitor();
I changed the initialization of handler_lock_ into a static initialization, that
should protect against multiple invocations of StartHandler.

On 2013/05/08 15:26:48, hausner wrote:
> What if two threads call this function by accident? Then there will be two
> locks, and one thread may have lock 1 while the second one grabs lock 2.
> 
> Not entirely safe, but maybe good enough: ASSERT(handler_lock_ == NULL) before
> allocating the lock.

[siva, 2013-05-08 21:27:58]

Committed patchset #2 manually as r22531 (presubmit successful).