Merge 217139 "[Mac] Change to detach the web contents view when ..."

chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm

Index: chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm
===================================================================
--- chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm	(revision 217358)
+++ chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm	(working copy)
@@ -803,17 +803,32 @@
 }
 
 - (void)windowDidResize:(NSNotification*)notification {
-  // Hide the web contents view when the panel is not taller than the titlebar.
-  // This is to ensure that the titlebar view is not overlapped with the web
-  // contents view because the the web contents view assumes that its
-  // view will never be overlapped by another view in order to perform
-  // optimization. If we do not do this, some part of the web contents view
-  // will become visible and overlapp the bottom area of the titlebar.
-  if (WebContents* contents = windowShim_->panel()->GetWebContents()) {
-    BOOL hideContents =
-        NSHeight([self contentRectForFrameRect:[[self window] frame]]) <=
-        panel::kTitlebarHeight;
-    [contents->GetView()->GetNativeView() setHidden:hideContents];
+  // Remove the web contents view from the view hierarchy when the panel is not
+  // taller than the titlebar. Put it back when the panel grows taller than
+  // the titlebar. Note that RenderWidgetHostViewMac works for the case that
+  // the web contents view does not exist in the view hierarchy (i.e. the tab
+  // is not the main one), but it does not work well, like causing occasional
+  // crashes (http://crbug.com/265932), if the web contents view is made hidden.
+  //
+  // The reason for doing this is to ensure that our titlebar view, that is
+  // somewhat taller than the standard titlebar, does not overlap with the web
+  // contents view because the the web contents view assumes that its view will
+  // never overlap with another view in order to paint the web contents view
+  // directly. If we do not do this, some part of the web contents view will
+  // become visible and overlap the bottom area of the titlebar.
+  content::WebContents* webContents = windowShim_->panel()->GetWebContents();
+  if (!webContents)
+    return;
+  NSView* contentView = webContents->GetView()->GetNativeView();
+  if (NSHeight([self contentRectForFrameRect:[[self window] frame]]) <=
+      panel::kTitlebarHeight) {
+    // No need to retain the view before it is removed from its superview
+    // because WebContentsView keeps a reference to this view.
+    if ([contentView superview])
+      [contentView removeFromSuperview];
+  } else {
+    if (![contentView superview])
+      [[[self window] contentView] addSubview:contentView];
   }
 }