MacViews: Clip contents for non-rectangular windows.

ui/views/cocoa/bridged_content_view.mm

Index: ui/views/cocoa/bridged_content_view.mm
diff --git a/ui/views/cocoa/bridged_content_view.mm b/ui/views/cocoa/bridged_content_view.mm
index 6022a44723bf99d9873d04bd6dcbebdb7bc66697..38c3fa47e9ab69268b3cd0f00c871a1076a84a65 100644
--- a/ui/views/cocoa/bridged_content_view.mm
+++ b/ui/views/cocoa/bridged_content_view.mm
@@ -228,6 +228,11 @@ gfx::Rect GetFirstRectForRangeHelper(const ui::TextInputClient* client,
   hostedView_ = nullptr;
   [cursorTrackingArea_.get() clearOwner];
   [self removeTrackingArea:cursorTrackingArea_.get()];
+  windowMask_.reset();
+}
+
+- (NSBezierPath*)windowMask {
+  return windowMask_.get();
 }
 
 - (void)processCapturedMouseEvent:(NSEvent*)theEvent {
@@ -268,8 +273,6 @@ gfx::Rect GetFirstRectForRangeHelper(const ui::TextInputClient* client,
 }
 
 - (void)updateWindowMask {
-  DCHECK(![self inLiveResize]);
-  DCHECK(base::mac::IsOSMavericksOrEarlier());
   DCHECK(hostedView_);
 
   views::Widget* widget = hostedView_->GetWidget();
@@ -435,13 +438,11 @@ gfx::Rect GetFirstRectForRangeHelper(const ui::TextInputClient* client,
 - (void)viewDidEndLiveResize {
   [super viewDidEndLiveResize];
 
-  // We prevent updating the window mask and clipping the border around the
-  // view, during a live resize. Hence update the window mask and redraw the
-  // view after resize has completed.
-  if (base::mac::IsOSMavericksOrEarlier()) {
-    [self updateWindowMask];
+  // During a live resize, we prevent clipping the border around the view, which
+  // is required to generate drop shadows on OSX 10.9. Hence redraw the view
+  // after resize has completed.
+  if (base::mac::IsOSMavericksOrEarlier())
     [self setNeedsDisplay:YES];
-  }
 }
 
 - (void)drawRect:(NSRect)dirtyRect {
@@ -464,8 +465,8 @@ gfx::Rect GetFirstRectForRangeHelper(const ui::TextInputClient* client,
   // boundary with clearColor and tell Cococa to regenerate drop shadow. See
   // crbug.com/543671.
   if (windowMask_ && ![self inLiveResize] &&
-      !IsRectInsidePath(dirtyRect, windowMask_)) {
-    DCHECK(base::mac::IsOSMavericksOrEarlier());
+      !IsRectInsidePath(dirtyRect, windowMask_) &&
+      base::mac::IsOSMavericksOrEarlier()) {
     gfx::ScopedNSGraphicsContextSaveGState state;
 
     // The outer rectangular path corresponding to the window.