[Mac] Improve modal sheet positioning during window resizing.

chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.h"
 
 #include <map>
 
 #include "base/logging.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet.h"
@@ skipping 17 matching lines @@
   base::scoped_nsobject<ConstrainedWindowSheetController> controller_;
 }
 @end
 
 @interface ConstrainedWindowSheetController ()
 - (id)initWithParentWindow:(NSWindow*)parentWindow;
 - (ConstrainedWindowSheetInfo*)findSheetInfoForParentView:(NSView*)parentView;
 - (ConstrainedWindowSheetInfo*)
     findSheetInfoForSheet:(id<ConstrainedWindowSheet>)sheet;
 - (void)onParentWindowWillClose:(NSNotification*)note;
-- (void)onParentViewFrameDidChange:(NSNotification*)note;
+- (void)onParentWindowSizeDidChange:(NSNotification*)note;
 - (void)updateSheetPosition:(NSView*)parentView;
 - (NSRect)overlayWindowFrameForParentView:(NSView*)parentView;
 - (NSPoint)originForSheetSize:(NSSize)sheetSize
               inContainerRect:(NSRect)containerRect;
 - (void)onOverlayWindowMouseDown:(CWSheetOverlayWindow*)overlayWindow;
 - (void)closeSheet:(ConstrainedWindowSheetInfo*)info
      withAnimation:(BOOL)withAnimation;
 @end
 
 @implementation CWSheetOverlayWindow
@@ skipping 74 matching lines @@
   return self;
 }
 
 - (void)showSheet:(id<ConstrainedWindowSheet>)sheet
     forParentView:(NSView*)parentView {
   DCHECK(sheet);
   DCHECK(parentView);
   if (!activeView_.get())
     activeView_.reset([parentView retain]);
 
-  // Observer the parent view's frame.
-  [parentView setPostsFrameChangedNotifications:YES];
+  // Observe the parent window's size.
   [[NSNotificationCenter defaultCenter]
       addObserver:self
-         selector:@selector(onParentViewFrameDidChange:)
-             name:NSViewFrameDidChangeNotification
-           object:parentView];
+         selector:@selector(onParentWindowSizeDidChange:)
+             name:NSWindowDidResizeNotification
+           object:parentWindow_];
 
   // Create an invisible overlay window.
   NSRect rect = [self overlayWindowFrameForParentView:parentView];
   base::scoped_nsobject<NSWindow> overlayWindow(
       [[CWSheetOverlayWindow alloc] initWithContentRect:rect controller:self]);
   [parentWindow_ addChildWindow:overlayWindow
                         ordered:NSWindowAbove];
 
   // Add an entry for the sheet.
   base::scoped_nsobject<ConstrainedWindowSheetInfo> info(
@@ skipping 71 matching lines @@
     [self closeSheet:info withAnimation:NO];
 
   // Delete this instance.
   [g_sheetControllers removeObjectForKey:GetKeyForParentWindow(parentWindow_)];
   if (![g_sheetControllers count]) {
     [g_sheetControllers release];
     g_sheetControllers = nil;
   }
 }
 
-- (void)onParentViewFrameDidChange:(NSNotification*)note {
-  NSView* parentView = [note object];
-  if (![activeView_ isEqual:parentView])
-    return;
-  [self updateSheetPosition:parentView];
+- (void)onParentWindowSizeDidChange:(NSNotification*)note {
+  [self updateSheetPosition:activeView_];
 }
 
 - (void)updateSheetPosition:(NSView*)parentView {
   ConstrainedWindowSheetInfo* info =
       [self findSheetInfoForParentView:parentView];
   if (!info)
     return;
 
   NSRect rect = [self overlayWindowFrameForParentView:parentView];
   [[info overlayWindow] setFrame:rect display:YES];
@@ skipping 40 matching lines @@
   }
 }
 
 - (void)closeSheet:(ConstrainedWindowSheetInfo*)info
      withAnimation:(BOOL)withAnimation {
   if (![sheets_ containsObject:info])
     return;
 
   [[NSNotificationCenter defaultCenter]
       removeObserver:self
-                name:NSViewFrameDidChangeNotification
-              object:[info parentView]];
+                name:NSWindowDidResizeNotification
+              object:parentWindow_];
 
   [parentWindow_ removeChildWindow:[info overlayWindow]];
   [[info sheet] closeSheetWithAnimation:withAnimation];
   [[info overlayWindow] close];
   [sheets_ removeObject:info];
 }
 
 @end