MacViews: Fix crash due to failed DCHECK in BridgedNativeWidget.

ui/views/cocoa/bridged_native_widget.mm

 // Copyright 2014 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 "ui/views/cocoa/bridged_native_widget.h"
 
 #import <objc/runtime.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 294 matching lines @@
 
   if (left_found) {
     return left_rank->second < right_rank->second ? NSOrderedAscending
                                                   : NSOrderedDescending;
   }
 
   // If both are unassociated, consider that order is not important
   return NSOrderedSame;
 }
 
+#if DCHECK_IS_ON()

[tapted, 2016/10/06 07:38:46]

dang it - typically this is required to avoid a "this is unused" warning (which
also only shows up once you get run on a bot that doesn't have DCHECKs :/). But
I guess we can just try without. So, lgtm with this #if removed as well :) (but
perhaps worth just building a is_debug = false build without DCHECKs to ensure
that's the case)

[karandeepb, 2016/10/07 01:03:57]

Yeah, so the arguments to the DCHECK macros are still compiled in, but not used
on RELEASE builds, which caused the failure.

+// Counts windows managed by a BridgedNativeWidget instance in the
+// |child_windows| array ignoring the windows added by AppKit.
+NSUInteger CountBridgedWindows(NSArray* child_windows) {
+  NSUInteger count = 0;
+  for (NSWindow* child in child_windows)
+    if ([[child delegate] isKindOfClass:[ViewsNSWindowDelegate class]])
+      ++count;
+
+  return count;
+}
+#endif
+
 }  // namespace
 
 namespace views {
 
 // static
 gfx::Size BridgedNativeWidget::GetWindowSizeForClientSize(
     NSWindow* window,
     const gfx::Size& content_size) {
   NSRect content_rect =
       NSMakeRect(0, 0, content_size.width(), content_size.height());
@@ skipping 858 matching lines @@
     for (BridgedNativeWidget* child : child_windows_) {
       if (child->window_visible_)
         [child->ns_window() orderOut:nil];
 
       DCHECK(!child->window_visible_);
       CHECK_EQ(child_count, child_windows_.size());
     }
     // The orderOut calls above should result in a call to OnVisibilityChanged()
     // in each child. There, children will remove themselves from the NSWindow
     // childWindow list as well as propagate NotifyVisibilityChangeDown() calls
-    // to any children of their own.
-    DCHECK_EQ(0u, [[window_ childWindows] count]);
+    // to any children of their own. However this is only true for windows
+    // managed by the BridgedNativeWidget i.e. windows which have
+    // ViewsNSWindowDelegate as the delegate.
+    DCHECK_EQ(0u, CountBridgedWindows([window_ childWindows]));
     return;
   }
 
-  NSUInteger visible_children = 0;  // For a DCHECK below.
+  NSUInteger visible_bridged_children = 0;  // For a DCHECK below.
   NSInteger parent_window_number = [window_ windowNumber];
   for (BridgedNativeWidget* child: child_windows_) {
     // Note: order the child windows on top, regardless of whether or not they
     // are currently visible. They probably aren't, since the parent was hidden
     // prior to this, but they could have been made visible in other ways.
     if (child->wants_to_be_visible_) {
-      ++visible_children;
+      ++visible_bridged_children;
       // Here -[NSWindow orderWindow:relativeTo:] is used to put the window on
       // screen. However, that by itself is insufficient to guarantee a correct
       // z-order relationship. If this function is being called from a z-order
       // change in the parent, orderWindow turns out to be unreliable (i.e. the
       // ordering doesn't always take effect). What this actually relies on is
       // the resulting call to OnVisibilityChanged() in the child, which will
       // then insert itself into -[NSWindow childWindows] to let Cocoa do its
       // internal layering magic.
       [child->ns_window() orderWindow:NSWindowAbove
                            relativeTo:parent_window_number];
       DCHECK(child->window_visible_);
     }
     CHECK_EQ(child_count, child_windows_.size());
   }
-  DCHECK_EQ(visible_children, [[window_ childWindows] count]);
+  DCHECK_EQ(visible_bridged_children,
+            CountBridgedWindows([window_ childWindows]));
 }
 
 gfx::Size BridgedNativeWidget::GetClientAreaSize() const {
   NSRect content_rect = [window_ contentRectForFrameRect:[window_ frame]];
   return gfx::Size(NSWidth(content_rect), NSHeight(content_rect));
 }
 
 void BridgedNativeWidget::CreateCompositor() {
   DCHECK(!compositor_);
   DCHECK(!compositor_widget_);
@@ skipping 159 matching lines @@
   [bridged_view_ setMouseDownCanMoveWindow:draggable];
   // AppKit will not update its cache of mouseDownCanMoveWindow unless something
   // changes. Previously we tried adding an NSView and removing it, but for some
   // reason it required reposting the mouse-down event, and didn't always work.
   // Calling the below seems to be an effective solution.
   [window_ setMovableByWindowBackground:NO];
   [window_ setMovableByWindowBackground:YES];
 }
 
 }  // namespace views