Revert of Adjusts dragging logic to be less likely to trigger false positive switch from snapping to docking

Revert of Adjusts dragging logic to be less likely to trigger false positive switch from snapping to docking (patchset #5 id:90001 of https://codereview.chromium.org/1127133003/)

Reason for revert:
I suspect this is causing a browser_tests failure on the bots:

http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/2069
https://build.chromium.org/p/chromium.webkit/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/1913

Sorry!

Original issue's description:
> Adjusts dragging logic to be less likely to trigger false positive switch from
> snapping to docking.
>
> This CL adjusts the logic which selects whether a window will be snapped to
> half of the workspace width or will be docked at the end of the drag when the
> window is dragged to the edge of the workspace in the special case of the dock
> being visible. The CL makes it easier to snap a window to half the workspace
> width in this special case (and harder to inadvertently dock the window)
>
> BUG=484877
> TEST=None
>
> Committed: https://crrev.com/988c697aff35b3fd347dec35f2f2ac159c8328a9
> Cr-Commit-Position: refs/heads/master@{#329268}

TBR=pkotwicz@chromium.org,varkha@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=484877
Committed: https://crrev.com/0d4f7d597774f7415f1aff374db498c8fbe88a9a
Cr-Commit-Position: refs/heads/master@{#329301}

[Dirk Pranke, 2015-05-12 00:51:06]

Created Revert of Adjusts dragging logic to be less likely to trigger false
positive switch from snapping to docking

[varkha, 2015-05-12 16:07:10]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1140733002/ by varkha@chromium.org.

The reason for reverting is: This revert probably did not cause the flakiness. I
suspect that this revert actually ended up fixing the bots:
https://codereview.chromium.org/1139943002.

I will re-land my original change..