Make <webview> use out-of-process iframe architecture.

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 d95b2aca43ea3ee4bb8d5f0776d6e5ff56aaf106..ad678234a4d84eaf810143592271017afe3370c6 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -277,6 +277,9 @@ class CONTENT_EXPORT WebContentsImpl
   void WasHidden() override;
   bool NeedToFireBeforeUnload() override;
   void DispatchBeforeUnload(bool for_cross_site_transition) override;
+  void AttachToOuterWebContentsFrame(
+      WebContents* outer_web_contents,
+      RenderFrameHost* outer_contents_frame) override;
   void Stop() override;
   WebContents* Clone() override;
   void ReloadFocusedFrame(bool ignore_cache) override;
@@ -592,6 +595,7 @@ class CONTENT_EXPORT WebContentsImpl
   bool FocusLocationBarByDefault() override;
   void SetFocusToLocationBar(bool select_all) override;
   bool IsHidden() override;
+  int GetOuterDelegateFrameTreeNodeID() override;
 
   // NotificationObserver ------------------------------------------------------
 
@@ -723,6 +727,26 @@ class CONTENT_EXPORT WebContentsImpl
 
   class DestructionObserver;
 
+  // Represents a WebContents node in a tree of WebContents structure.
+  //
+  // Two WebContents with separate FrameTrees can be connected by
+  // outer/inner relationship using this class. Note that their FrameTrees
+  // still remain disjoint.
+  // The root is referred to as "outer WebContents" and the descendents are
+  // referred to as "inner WebContents".
+  struct WebContentsTreeNode {
+   public:
+    WebContentsTreeNode();
+    ~WebContentsTreeNode();
+
+    void SetOuterWebContents(WebContentsImpl* outer_web_contents);
+    WebContentsImpl* outer_web_contents() { return outer_web_contents_; }
+
+   private:
+    WebContentsImpl* outer_web_contents_;
+    std::set<WebContentsTreeNode*> inner_web_contents_tree_nodes_;

[nasko, 2015/05/28 22:13:46]

Why does the outer WebContents need to know about the inner ones? It doesn't
seem we use this anywhere but to clear pointers during destruction.

[lazyboy, 2015/05/29 00:02:24]

The outer WebContents(TreeNode) may be destroyed before its children,
so this allows us to remove stale pointers to outer from those children.

+  };
+
   // See WebContents::Create for a description of these parameters.
   WebContentsImpl(BrowserContext* browser_context,
                   WebContentsImpl* opener);
@@ -1037,6 +1061,10 @@ class CONTENT_EXPORT WebContentsImpl
   // Manages the frame tree of the page and process swaps in each node.
   FrameTree frame_tree_;
 
+  // If this WebContents is part of a "tree of WebContents", then this contains
+  // information about the structure.
+  WebContentsTreeNode node_;
+
   // SavePackage, lazily created.
   scoped_refptr<SavePackage> save_package_;