Move the "import find_depot_tools" line to sections that actually use it.

This shrinks the dependency of depot_tools to only Windows and Cygwin, and allows those on other OSes to just build tarballs of sources without also having the depot_tools.

BUG=none

Review URL: https://codereview.chromium.org/171513010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252434 0039d316-1c4b-4281-b951-d872f2087c98
Fix a crasher in the BrowserAccessibilityWin::get_accParent function which occurs because
of a CHECK firing for the parent IAccessible interface pointer.

Based on a discussion with dmazzoni, the original reason for this CHECK being added has
been fixed which was a race condition in creation of the manager before the parent IAccessible
interface got created.

The parent IAccessible pointer can be NULL during destruction which we need to handle.

Fix is to return E_FAIL if the parent IAccessible pointer is NULL along with a log statement
for debugging.

BUG=345463,345328
R=dmazzoni@chromium.org

Review URL: https://codereview.chromium.org/174293003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252435 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252435