Mac: Make calling WebContents::WasShown/WasHidden the responsibility of the content layer

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index 79c0c86e2b34d8b5df32c2775f16e94cb3222efd..266e3efb32e2fc62b34474e823879cbdce6ec4c9 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -728,6 +728,9 @@ class CONTENT_EXPORT WebContentsImpl
     return media_web_contents_observer_.get();
   }
 
+  // Update the web contents visibility.
+  void UpdateWebContentsVisibility(bool visible);
+
  private:
   friend class WebContentsObserver;
   friend class WebContents;  // To implement factory methods.
@@ -1166,6 +1169,12 @@ class CONTENT_EXPORT WebContentsImpl
   // Tracks whether RWHV should be visible once capturer_count_ becomes zero.
   bool should_normally_be_visible_;
 
+  // Tracks whether this WebContents was ever set to be visible. Used to
+  // facilitate WebContents being loaded in the background by setting
+  // |should_normally_be_visible_|. Ensures WasShown() will trigger when first
+  // becoming visible to the user, and prevents premature unloading.
+  bool did_first_set_visible_;
+
   // See getter above.
   bool is_being_destroyed_;