Parameterize the composited RenderWidgetHostViewBrowserTests.

Run these tests with both hardware and software compositing. When
software compositing is enabled for a browser test, it also sets
appropriate command line flags to ensure the renderer is software
composited and the ui compositor is single-threaded.

R=piman@chromium.org
BUG=327508

Review URL: https://codereview.chromium.org/116893004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242080 0039d316-1c4b-4281-b951-d872f2087c98
drive: Move FileSystem::LoadDirectoryIfNeeded() to ChangeListLoader

ChangeListLoader::LoadIfNeeded()'s only user in the production code is FileSystem::LoadDiretoryIfNeeded().
It means that only test related code is passing empty DirectoryFetchInfo for LoadIfNeeded().

Move FileSystem::LoadDirectoryIfNeeded() to ChangeListLoader.
Merge LoadIfNeeded() to LoadDirectoryIfNeeded().
Add LoadForTesting() for the sake of test code.

BUG=260526
TEST=unit_tests

Review URL: https://codereview.chromium.org/118993002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242081 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242081