Converts BaseView to be non-opaque, which will fix drawing of...

Converts BaseView to be non-opaque, which will fix drawing of
overlapping views, including the findbar and resize widget.  Three
classes currently inherit from BaseView: TabContentsViewCocoa,
RenderWidgetHostViewCocoa, and SadTabView (Mac).

BUG=http://crbug.com/10887
BUG=http://crbug.com/13150
TEST=Findbar should never disappear when searching.  Resize
widget should never disappear.  Clicking and dragging in a webpage should not move the window around.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=19725

[Avi (use Gerrit), 2009-06-30 15:29:21]

LG

[pink (ping after 24hrs), 2009-06-30 15:33:43]

LGTM

[pink (ping after 24hrs), 2009-06-30 16:24:24]

This breaks scrolling. It causes any click to drag the window.

[rohitrao (ping after 24h), 2009-06-30 23:04:37]

http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/Class...
is the magic secret.

So I think because we have a textured window, any mouseDown's in non-opaque
windows are treated as window-moving.  With my previous cl, that included every
single view, except for maybe the buttons, which (I think) get away with it
because they run nested message loops.

I'm going to override this in TabContentsViewCocoa, because BaseView seems like
the wrong place for it and I don't want to have to override it in every subview
of TCVCocoa.  We can revisit if that turns out to break something.

This is ready for another look.

[pink (ping after 24hrs), 2009-07-01 13:15:09]

LGTM

[Avi (use Gerrit), 2009-07-01 14:20:17]

Nice! LGTM