DLP: Move data transfer files to a separate dir

Given that data_transfer_* files will be used for
clipboard and drag-and-drop, so
- Moved data_transfer_endpoint.h/.cc and
data_transfer_filter.h/.cc files from
ui/base/clipboard to ui/base/data_transfer_filter
- Added a new build target for DLP files
to be able to include them in base/dragdrop
without depending on :clipboard.

Bug: 1142426
Change-Id: I10106912a91216bf2d7347b3d0da9bb88883a4ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2498542
Commit-Queue: Aya Elsayed <ayaelattar@chromium.org>
Reviewed-by: Sergey Poromov <poromov@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822118}

• ash/clipboard/clipboard_history.cc[diff]
• ash/clipboard/clipboard_history_controller_impl.cc[diff]
• ash/clipboard/clipboard_history_menu_model_adapter.cc[diff]
• chrome/browser/chromeos/policy/dlp/data_transfer_dlp_controller.cc[diff]
• chrome/browser/chromeos/policy/dlp/data_transfer_dlp_controller.h[diff]
• chrome/browser/password_manager/chrome_password_manager_client.cc[diff]
• chrome/browser/renderer_context_menu/copy_link_to_text_menu_observer.cc[diff]
• chrome/browser/renderer_context_menu/render_view_context_menu.cc[diff]
• chrome/browser/ui/ash/clipboard_history_browsertest.cc[diff]
• chrome/browser/ui/omnibox/clipboard_utils.cc[diff]
• components/arc/clipboard/arc_clipboard_bridge.cc[diff]
• components/bookmarks/browser/bookmark_utils.cc[diff]
• components/exo/data_offer.cc[diff]
• components/exo/seat.cc[diff]
• components/open_from_clipboard/DEPS[diff]
• components/open_from_clipboard/clipboard_recent_content_generic.cc[diff]
• content/browser/renderer_host/clipboard_host_impl.cc[diff]
• content/browser/renderer_host/input/touch_selection_controller_client_aura.cc[diff]
• content/browser/renderer_host/input/touch_selection_controller_client_child_frame.cc[diff]
• content/browser/renderer_host/raw_clipboard_host_impl.cc[diff]
• headless/lib/browser/headless_clipboard.cc[diff]
• headless/lib/browser/headless_clipboard.h[diff]
• remoting/host/chromeos/clipboard_aura.cc[diff]
• ui/base/BUILD.gn[diff]
• ui/base/clipboard/BUILD.gn[diff]
• ui/base/clipboard/clipboard.h[diff]
• ui/base/clipboard/clipboard_android.cc[diff]
• ui/base/clipboard/clipboard_data.cc[diff]
• ui/base/clipboard/clipboard_data.h[diff]
• ui/base/clipboard/clipboard_data_endpoint.cc[diff]
• ui/base/clipboard/clipboard_data_unittest.cc[diff]
• ui/base/clipboard/clipboard_mac.mm[diff]
• ui/base/clipboard/clipboard_non_backed.cc[diff]
• ui/base/clipboard/clipboard_ozone.cc[diff]
• ui/base/clipboard/clipboard_test_template.h[diff]
• ui/base/clipboard/clipboard_win.cc[diff]
• ui/base/clipboard/clipboard_x11.cc[diff]
• ui/base/clipboard/scoped_clipboard_writer.h[diff]
• ui/base/clipboard/test/test_clipboard.cc[diff]
• ui/base/clipboard/test/test_clipboard.h[diff]
• ui/base/data_transfer_policy/BUILD.gn[Added - diff]
• ui/base/data_transfer_policy/DIR_METADATA[Added - diff]
• ui/base/data_transfer_policy/OWNERS[Added - diff]
• ui/base/data_transfer_policy/data_transfer_endpoint.cc[Renamed from ui/base/clipboard/data_transfer_endpoint.cc - diff]
• ui/base/data_transfer_policy/data_transfer_endpoint.h[Renamed from ui/base/clipboard/data_transfer_endpoint.h - diff]
• ui/base/data_transfer_policy/data_transfer_policy_controller.cc[Renamed from ui/base/clipboard/data_transfer_policy_controller.cc - diff]
• ui/base/data_transfer_policy/data_transfer_policy_controller.h[Renamed from ui/base/clipboard/data_transfer_policy_controller.h - diff]
• ui/views/controls/textfield/textfield.cc[diff]