The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/20e8fb18e771067d5cbbb1e22d7fc6c19c4b4d3a

commit 20e8fb18e771067d5cbbb1e22d7fc6c19c4b4d3a
Author: joedow <joedow@chromium.org>
Date: Tue Nov 08 23:27:58 2016

Always consider SystemUI for panning boundaries in split-screen mode

This change allows the user to pan the desktop out from under System UI
when in windowed/split-screen mode.  In fullscreen mode, we only allow
this behavior when the Soft Keyboard is present.  For N+, we need to
allow the user to pan out from under System UI as it is always present
in this mode (unlike fullscreen where the UI will autohide).

This CL moves the logic for determining when to allow 'over-panning' to
the Desktop activity (from the DesktopCanvas class).  The Desktop class
is a better place for this logic as it is aware of more state
information and should own the end user experience (whereas the
DesktopCanvas class should only handle boundary and viewport
calculations).

I've also updated the offset reduction animation code to allow it to
animate to a specific offset (instead of a hard-coded 0, 0).  This
functionality is used when the size of the System UI is reduced to a
non-zero value.  An example of this is when the toolbar auto-hides but
the status bar is still displayed.  In that case we want the desktop
image to be animated upwards (reducing the amount of viewport offset)
but we don't want to animate to the top of the screen, just to the
bottom of the status bar.

BUG= 662458 

Review-Url: https://codereview.chromium.org/2485143004
Cr-Commit-Position: refs/heads/master@{#430755}

[modify] https://crrev.com/20e8fb18e771067d5cbbb1e22d7fc6c19c4b4d3a/remoting/android/java/src/org/chromium/chromoting/Desktop.java
[modify] https://crrev.com/20e8fb18e771067d5cbbb1e22d7fc6c19c4b4d3a/remoting/android/java/src/org/chromium/chromoting/DesktopCanvas.java
[modify] https://crrev.com/20e8fb18e771067d5cbbb1e22d7fc6c19c4b4d3a/remoting/android/java/src/org/chromium/chromoting/SystemUiVisibilityChangedEventParameter.java

Verified Fixed in 56.0.2913.4. Screen is pannable in split screen mode. No regressions were found. Other activities, such as dragging items while panning and zooming then panning also work correctly.