To explain it clearly: Look at the snapshot for Linux:
1. We use bold title and an "orange" image border to represent selection
2. We use a light dark background color to represent mouse hovering.

Deleted: WindowCaptureLinux.png 85.3 KB

	WindowCaptureLinux.png 85.3 KB View Download

Actually, we did not hard code the selection border color or the hovering bg color. They are pulled from theme.

More specifically, 
the selection border color is kColorId_FocusedMenuItemBackgroundColor, 
and the hovering bg color is kColorId_HoverMenuItemBackgroundColor.

But the setting does not work well with Windows.
1. The selection border color is light gray.
2. The hovering bg color is white, and thus invisible.

Deleted: WindowCaptureWin.PNG 54.0 KB

	WindowCaptureWin.PNG 54.0 KB View Download

msw@: Do you have any idea about how to work this around?

Look at ui/views/controls/tree/ and ui/views/controls/table.
TableView and TreeView show selected items with background colors like:
  ui::NativeTheme::kColorId_TableSelectionBackgroundFocused
  ui::NativeTheme::kColorId_TreeSelectionBackgroundUnfocused
I suggest re-using *all* colors from one of these controls (replace all current colors).

Also, maybe don't change the colors for hovering? (tree and table don't do this)
Or, if you really want a hover color, perhaps blend selected and normal or similar?

Thanks. I found the Color setting for TableView works for both OS.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4b2cc3e651652b3bab2ed52c33488ebad57731e4

commit 4b2cc3e651652b3bab2ed52c33488ebad57731e4
Author: qiangchen <qiangchen@chromium.org>
Date: Mon Sep 12 17:21:41 2016

Desktop Capture Picker: More Clear Selection

We set border color for source item to indicate it is selected.
But the color is just light grey on Windows and ChromeOS, and thus
hardly visible.

We changed to use kColorId_FocusedBorderColor, which looks good
on all platforms.

BUG= 643292 

Review-Url: https://codereview.chromium.org/2323913002
Cr-Commit-Position: refs/heads/master@{#417964}

[modify] https://crrev.com/4b2cc3e651652b3bab2ed52c33488ebad57731e4/chrome/browser/ui/views/desktop_capture/desktop_media_picker_views.cc
[modify] https://crrev.com/4b2cc3e651652b3bab2ed52c33488ebad57731e4/chrome/browser/ui/views/desktop_capture/desktop_media_source_view.cc
[modify] https://crrev.com/4b2cc3e651652b3bab2ed52c33488ebad57731e4/chrome/browser/ui/views/desktop_capture/desktop_media_source_view.h

Run Desktop Capture Picker Window on Windows and ChromeOS.

The selection border should be blue.

Your change meets the bar and is auto-approved for M54 (branch: 2840)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71

commit c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71
Author: qiangchen <qiangchen@chromium.org>
Date: Tue Sep 13 21:01:18 2016

Desktop Capture Picker: More Clear Selection

We set border color for source item to indicate it is selected.
But the color is just light grey on Windows and ChromeOS, and thus
hardly visible.

We changed to use kColorId_FocusedBorderColor, which looks good
on all platforms.

BUG= 643292 

TBR=msw@chromium.org
NOPRESUBMIT=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2323913002
Cr-Commit-Position: refs/heads/master@{#417964}
(cherry picked from commit 4b2cc3e651652b3bab2ed52c33488ebad57731e4)

Review-Url: https://codereview.chromium.org/2335373002
Cr-Commit-Position: refs/branch-heads/2840@{#340}
Cr-Branched-From: 1ae106dbab4bddd85132d5b75c670794311f4c57-refs/heads/master@{#414607}

[modify] https://crrev.com/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71/chrome/browser/ui/views/desktop_capture/desktop_media_picker_views.cc
[modify] https://crrev.com/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71/chrome/browser/ui/views/desktop_capture/desktop_media_source_view.cc
[modify] https://crrev.com/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71/chrome/browser/ui/views/desktop_capture/desktop_media_source_view.h

Retested the above issue on Ubuntu 14.04 with chrome version '54.0.2840.27' and border color gets displayed as orange when the item is selected in Desktop capture picker. Hence marking the same as TE-Verified-54.0.2840.27.

Attach is the screenshot for the same.

Thank you!

Deleted: Screenshot from 2016-09-14 17:59:50.png 284 KB

	Screenshot from 2016-09-14 17:59:50.png 284 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71

commit c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71
Author: qiangchen <qiangchen@chromium.org>
Date: Tue Sep 13 21:01:18 2016

Desktop Capture Picker: More Clear Selection

We set border color for source item to indicate it is selected.
But the color is just light grey on Windows and ChromeOS, and thus
hardly visible.

We changed to use kColorId_FocusedBorderColor, which looks good
on all platforms.

BUG= 643292 

TBR=msw@chromium.org
NOPRESUBMIT=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2323913002
Cr-Commit-Position: refs/heads/master@{#417964}
(cherry picked from commit 4b2cc3e651652b3bab2ed52c33488ebad57731e4)

Review-Url: https://codereview.chromium.org/2335373002
Cr-Commit-Position: refs/branch-heads/2840@{#340}
Cr-Branched-From: 1ae106dbab4bddd85132d5b75c670794311f4c57-refs/heads/master@{#414607}

[modify] https://crrev.com/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71/chrome/browser/ui/views/desktop_capture/desktop_media_picker_views.cc
[modify] https://crrev.com/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71/chrome/browser/ui/views/desktop_capture/desktop_media_source_view.cc
[modify] https://crrev.com/c43f5d39d135bb0ce1d18eb41d8770b8eadb8c71/chrome/browser/ui/views/desktop_capture/desktop_media_source_view.h