Remove WebContents::Was{Hidden,Shown}() from the content public interface

content/public/browser/web_contents.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 364 matching lines @@
 
   // Convenience method for notifying the delegate of a navigation state
   // change.
   virtual void NotifyNavigationStateChanged(InvalidateTypes changed_flags) = 0;
 
   // Get/Set the last time that the WebContents was made active (either when it
   // was created or shown with WasShown()).
   virtual base::TimeTicks GetLastActiveTime() const = 0;
   virtual void SetLastActiveTime(base::TimeTicks last_active_time) = 0;
 
-  // Invoked when the WebContents becomes shown/hidden.
-  virtual void WasShown() = 0;
-  virtual void WasHidden() = 0;
+  // Hides the RenderWidgetHostView if it is not being used for capture, and
+  // emits WebContentsObserver::WasHidden().
+  virtual void MarkBackgrounded() = 0;

[jam, 2016/02/29 17:36:36]

what's the other analogous method?

i.e. it seems this is for undoing a previous call.where is that call?
shouldn't they be together?

[tapted, 2016/02/29 22:42:32]

Ah, that's the thing :). `MarkBackgrounded` actually shouldn't exist, and
embedders don't really need the analogous method. That's because they're
currently using calls to WebContents::WasHidden() shortly after creating a
WebContents, but with that WebContents created with
WebContents::InitParams::initially_hidden set to false, rather than true. For
Aura platforms, the `WasShown` call to balance a WasHidden is always made by the
content layer, by WebContentsView. (and http://crrev.com/1733173002 makes that
true for Mac as well as Aura).

Exposing `WasHidden` can lead to bugs - e.g. http://crbug.com/590476 which came
up recently. Part of the issue is that calls to `WasHidden` (or MarkBackgrounded
which this CL renames it to) can be called on WebContents that are already
hidden.

This CL annotates all the `WasHidden` calls that Chrome was making. I think they
can all be removed with appropriate use of
WebContents::InitParams::initially_hidden . (Or perhaps
`InitParams::initial_state = {BACKGROUND_PRELOAD, FOREGROUND}` if that's
clearer. Maybe there's a use case for `UNLOADED` as well, but there doesn't seem
to be).

 
   // Returns true if the before unload and unload listeners need to be
   // fired. The value of this changes over time. For example, if true and the
   // before unload listener is executed and allows the user to exit, then this
   // returns false.
   virtual bool NeedToFireBeforeUnload() = 0;
 
   // Runs the beforeunload handler for the main frame. See also ClosePage and
   // SwapOut in RenderViewHost, which run the unload handler.
   //
@@ skipping 321 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class WebContentsImpl;
   WebContents() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_