Move WebUI ownership from the RenderFrameHostManager to the RenderFrameHost.

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index ec3dd50746f54871fd3ee21036323a4d78d3edb6..74ca211f580e36b2bea76dffe366d1788a276382 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -16,6 +16,7 @@
 #include "base/time/time.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/site_instance_impl.h"
+#include "content/browser/webui/web_ui_impl.h"
 #include "content/common/accessibility_mode_enums.h"
 #include "content/common/ax_content_node_data.h"
 #include "content/common/content_export.h"
@@ -212,6 +213,14 @@ class CONTENT_EXPORT RenderFrameHostImpl
   RenderFrameHostDelegate* delegate() { return delegate_; }
   FrameTreeNode* frame_tree_node() { return frame_tree_node_; }
 
+  // Returns the associated Web UI or nullptr if none applies.
+  WebUIImpl* web_ui() const { return web_ui_.get(); }
+
+  // Returns the pending associated Web UI, or nullptr of none applies.
+  WebUIImpl* pending_web_ui() const {
+    return should_reuse_web_ui_ ? web_ui_.get() : pending_web_ui_.get();
+  }
+
   // Returns this RenderFrameHost's loading state. This method is only used by
   // FrameTreeNode. The proper way to check whether a frame is loading is to
   // call FrameTreeNode::IsLoading.
@@ -464,6 +473,25 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // addition, its associated RenderWidgetHost has to be focused.
   bool IsFocused();
 
+  // Initializes the first WebUI for a recently created RenderFrameHost, if one
+  // is required by |dest_url|. No WebUI must have been set before and it must
+  // be called only once. If this is a history navigation to an existing
+  // NavigationEntry, providing its |past_bindings| will allow verifying that
+  // bindings are not being set differently this time around.

[clamy, 2015/10/01 13:15:13]

If it's not a history entry, what should the value of past_bindings be?

[carlosk, 2015/10/01 16:00:22]

This method was removed.

+  void InitializeWebUI(const GURL& dest_url, int past_bindings);
+
+  // Creates or replaces the pending WebUI for this RFH. Same logic from
+  // InitializeWebUI applies for the provided parameters. If the new WebUI to be
+  // created matches the current active or existing existing ones, they will be
+  // reused.

[clamy, 2015/10/01 13:15:13]

Should you also provide past bindings when navigating to a history entry?

[carlosk, 2015/10/01 16:00:22]

I improved all WebUI methods comments to make them clearer.

+  void UpdatePendingWebUI(const GURL& dest_url, int past_bindings);
+
+  // Replaces the active WebUI with the pending one.
+  void CommitPendingWebUI();
+
+  // Destroy the pending WebUI and cleans up any related data.
+  void DiscardPendingWebUI();
+
   // Returns the Mojo ImageDownloader service.
   const image_downloader::ImageDownloaderPtr& GetMojoImageDownloader();
 
@@ -610,6 +638,15 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // frames, it will return the current frame's view.
   RenderWidgetHostViewBase* GetViewForAccessibility();
 
+  // Creates a WebUI object for the given URL if one applies and sets
+  // |web_ui_type| to its type, also ensuring that its bindings match
+  // |past_bindings| (if provided and different than
+  // NavigationEntryImpl::kInvalidBindings). If no WebUI applies, returns
+  // nullptr and resets web_ui_type to WebUI::kNoWebUI. .
+  scoped_ptr<WebUIImpl> CreateWebUI(const GURL& dest_url,
+                                    int past_bindings,
+                                    WebUI::TypeID* web_ui_type);
+
   // For now, RenderFrameHosts indirectly keep RenderViewHosts alive via a
   // refcount that calls Shutdown when it reaches zero.  This allows each
   // RenderFrameHostManager to just care about RenderFrameHosts, while ensuring
@@ -778,6 +815,21 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // NavigationHandle for it is owned by the NavigationRequest.
   scoped_ptr<NavigationHandleImpl> navigation_handle_;
 
+  // The associated WebUIImpl and its type. They will be set if the current page
+  // is a Web UI page. Otherwise they will be nullptr and WebUI::kNoWebUI,
+  // respectively.
+  scoped_ptr<WebUIImpl> web_ui_;

[clamy, 2015/10/01 13:15:13]

Would it be possible to modify the WebUI so that it returns its type. It's a bit
annoying to have to store those 2 parameters together.

[carlosk, 2015/10/01 16:00:22]

I agree and it is possible. But nasko@ mentioning once that having GetType
methods is discouraged and it would be needed in that case. So nasko@, WDYT?

+  WebUI::TypeID web_ui_type_;
+
+  // Stores a pending WebUIImpl and its type. These will only be set during a
+  // same-site navigation to a WebUI page (reusing this RenderFrameHost).
+  scoped_ptr<WebUIImpl> pending_web_ui_;
+  WebUI::TypeID pending_web_ui_type_;
+
+  // If true at commit time the current WebUI will simply be reused (no pending
+  // one will exist to be committed).

[clamy, 2015/10/01 13:15:13]

Then, is it equivalent to !pending_web_ui_?

[carlosk, 2015/10/01 16:00:22]

No because if this is false and the pending WebUI is nullptr, that will cause
the current WebUI to be destroyed and none to be put in its place.

+  bool should_reuse_web_ui_;
+
   // NOTE: This must be the last member.
   base::WeakPtrFactory<RenderFrameHostImpl> weak_ptr_factory_;