Remove the private methods from ScrollableArea on RenderLayer

These methods were not used as they were private so could be
safely removed. While cleaning up, removed also some extra
unused scaffolding methods from the refactoring and moved
m_cachedOverlayScrollbarOffset to RenderLayerScrollableArea.

BUG=260899

Review URL: https://codereview.chromium.org/25577002

git-svn-id: svn://svn.chromium.org/blink/trunk@158667 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Explode wtf/tests

Rather than putting all the unit tests in one folder, the current style is to
match Chromium and put the unit tests next to the code that they test. As a
side benefit, I won't typo text/test or mistake the testing StringImpl.cpp for
the normal StringImpl.cpp when usting Ctrl-P in Sublime anymore.

R=jamesr

Review URL: https://codereview.chromium.org/25414004

git-svn-id: svn://svn.chromium.org/blink/trunk@158668 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move UUID.cpp/.h to Source/platform/

BUG=297477

Review URL: https://codereview.chromium.org/25591002

git-svn-id: svn://svn.chromium.org/blink/trunk@158669 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move core/platform/sql into modules/webdatabase

This code is specific to webdatabase. There isn't any particular reason to move
it to blink_platform.dll, which would entail removing dependencies from this
code back into the webdatabase module.

I've also renamed the folder to sqlite to indiciate that this code is specific
to sqlite. I've also removed a few unnessary mentions of the word "Chromium"
from various names.

BUG=297477
R=eseidel

Review URL: https://codereview.chromium.org/25223002

git-svn-id: svn://svn.chromium.org/blink/trunk@158670 bbb929c8-8fbe-4397-9dbb-9b2b20218538