GitLab

remoting.ClientPluginImpl has grown organically over the years and become
a dumping ground of all functionality related to the plugin.

This CL moves all  host desktop related implementation from
remoting.ClientPluginImpl into remoting.ClientPlugin.HostDesktopImpl.

BUG=457890
NOTRY=true
TEST=Unit test passed locally and manually verified ShrinkToFit, bumpScrolling and resizeToClient works

Review URL: https://codereview.chromium.org/929323003

Cr-Commit-Position: refs/heads/master@{#317187}