[mac] Implement {frame: 'none'} app window on Mac.

content/browser/web_contents/web_contents_view_mac.mm

Index: content/browser/web_contents/web_contents_view_mac.mm
diff --git a/content/browser/web_contents/web_contents_view_mac.mm b/content/browser/web_contents/web_contents_view_mac.mm
index 023cd506255d7ee7f9cd4fea7c6c7b6b4b5ca405..b3a14f679717f4dd615ac8b4ab00a2c0b543ec17 100644
--- a/content/browser/web_contents/web_contents_view_mac.mm
+++ b/content/browser/web_contents/web_contents_view_mac.mm
@@ -330,6 +330,10 @@ gfx::Rect WebContentsViewMac::GetViewBounds() const {
   return gfx::Rect();
 }
 
+void WebContentsViewMac::SetMouseDownCanMoveWindow(bool can_move) {
+  [cocoa_view_ setMouseDownCanMoveWindow:can_move];
+}
+
 void WebContentsViewMac::CloseTab() {
   web_contents_->Close(web_contents_->GetRenderViewHost());
 }
@@ -412,6 +416,10 @@ void WebContentsViewMac::CloseTab() {
   }
 }
 
+- (void)setMouseDownCanMoveWindow:(BOOL)canMove {
+  mouseDownCanMoveWindow_ = canMove;
+}
+
 - (BOOL)mouseDownCanMoveWindow {
   // This is needed to prevent mouseDowns from moving the window
   // around.  The default implementation returns YES only for opaque
@@ -419,7 +427,7 @@ void WebContentsViewMac::CloseTab() {
   // its subviews do paint their entire frames.  Returning NO here
   // saves us the effort of overriding this method in every possible
   // subview.
-  return NO;
+  return mouseDownCanMoveWindow_;
 }
 
 - (void)pasteboard:(NSPasteboard*)sender provideDataForType:(NSString*)type {