PlzNavigate: Speculatively spawns a renderer process for navigations.

content/browser/frame_host/render_frame_host_manager.h

Index: content/browser/frame_host/render_frame_host_manager.h
diff --git a/content/browser/frame_host/render_frame_host_manager.h b/content/browser/frame_host/render_frame_host_manager.h
index ae8d9f9ddc4ff6cd18c405da388ebe0e6334e09a..4ad245d7d3e063824bf951c007caafad64b40190 100644
--- a/content/browser/frame_host/render_frame_host_manager.h
+++ b/content/browser/frame_host/render_frame_host_manager.h
@@ -20,6 +20,7 @@
 #include "content/public/common/referrer.h"
 #include "ui/base/page_transition_types.h"
 
+struct FrameHostMsg_BeginNavigation_Params;
 struct FrameMsg_Navigate_Params;
 
 namespace content {
@@ -34,14 +35,13 @@ class NavigationEntryImpl;
 class RenderFrameHost;
 class RenderFrameHostDelegate;
 class RenderFrameHostImpl;
-class RenderFrameHostManagerTest;
 class RenderFrameProxyHost;
 class RenderViewHost;
 class RenderViewHostImpl;
 class RenderWidgetHostDelegate;
 class RenderWidgetHostView;
-class TestWebContents;
 class WebUIImpl;
+struct CommonNavigationParams;
 
 // Manages RenderFrameHosts for a FrameTreeNode. It maintains a
 // current_frame_host() which is the content currently visible to the user. When
@@ -366,12 +366,24 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
   // RenderFrameHostManager. Returns MSG_ROUTING_NONE if none is found.
   int GetRoutingIdForSiteInstance(SiteInstance* site_instance);
 
-  // PlzNavigate: Called when a navigation is ready to commit, to select the
-  // renderer that will commit it.
+  // PlzNavigate
+  // Notifies the RFHM that a navigation is about to begin so that it can
+  // speculatively spawn a new renderer process if needed.
+  void BeginNavigation(const FrameHostMsg_BeginNavigation_Params& params,
+                       const CommonNavigationParams& common_params);
+
+  // PlzNavigate
+  // Called when a navigation is ready to commit, to select the renderer that
+  // will commit it.
   RenderFrameHostImpl* GetFrameHostForNavigation(const GURL& url,
                                                  ui::PageTransition transition);
 
+  // PlzNavigate
+  // Cancels any ongoing navigation.
+  void CleanUpNavigation();
+
  private:
+  friend class NavigatorTestWithBrowserSideNavigation;
   friend class RenderFrameHostManagerTest;
   friend class TestWebContents;
 
@@ -466,6 +478,16 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
                                                         int frame_routing_id,
                                                         int flags);
 
+  // PlzNavigate
+  // Creates a new RenderFrameHost and does all required supporting work for the
+  // speculative creation of a new renderer for an ongoing navigation request.
+  // This RenderFrameHost might be destroyed later if the final navigation
+  // destination doesn't match the initial one.
+  bool CreateSpeculativeRenderFrameHost(const GURL& url,
+                                        SiteInstance* old_instance,
+                                        SiteInstance* new_instance,
+                                        int bindings);
+
   // Sets up the necessary state for a new RenderViewHost with the given opener,
   // if necessary.  It creates a RenderFrameProxy in the target renderer process
   // with the given |proxy_routing_id|, which is used to route IPC messages when
@@ -485,6 +507,8 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
   // Sets the pending RenderFrameHost/WebUI to be the active one. Note that this
   // doesn't require the pending render_frame_host_ pointer to be non-NULL,
   // since there could be Web UI switching as well. Call this for every commit.
+  // If PlzNavigate is enabled the method will set the speculative
+  // RenderFrameHost to be the active one instead of the pending.
   void CommitPending();
 
   // Runs the unload handler in the old RenderFrameHost, after the new
@@ -531,6 +555,13 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
   // for the given |instance|.
   void DeleteRenderFrameProxyHost(SiteInstance* instance);
 
+  // PlzNavigate
+  // Returns the speculative RenderFrameHost or nullptr if there is no pending
+  // one.
+  RenderFrameHostImpl* speculative_render_frame_host() const {
+    return speculative_render_frame_host_.get();
+  }
+
   // For use in creating RenderFrameHosts.
   FrameTreeNode* frame_tree_node_;
 
@@ -602,6 +633,21 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
 
   base::WeakPtrFactory<RenderFrameHostManager> weak_factory_;
 
+  // PlzNavigate
+  // Members to store the speculative RFH created upon starting a navigation
+  // allowing the creation of the renderer process as early as possible.
+  // The created instance might be discarded later on if the final URL's
+  // SiteInstance isn't compatible with what was used to create it.
+  // Note: speculative RenderFrameHost is only used for PlzNavigate and the
+  // pending one only for the regular navigation.
+  scoped_ptr<RenderFrameHostImpl> speculative_render_frame_host_;
+  scoped_ptr<WebUIImpl> speculative_web_ui_;
+
+  // PlzNavigate
+  // If true at navigation commit time the current WebUI will be kept instead of
+  // creating a new one.
+  bool should_reuse_web_ui_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderFrameHostManager);
 };