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..b9791cf49b253c191b2fc14585b463390b41228b 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 {
@@ -31,6 +32,7 @@ class InterstitialPageImpl;
 class NavigationControllerImpl;
 class NavigationEntry;
 class NavigationEntryImpl;
+class NavigatorTestWithBrowserSideNavigation;
 class RenderFrameHost;
 class RenderFrameHostDelegate;
 class RenderFrameHostImpl;
@@ -42,6 +44,7 @@ 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 +369,24 @@ 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

[nasko, 2014/12/10 23:11:34]

nit: s/about to begin/has begun/ since we issue the network request before
calling into RFHM.

[carlosk, 2014/12/16 01:53:48]

Done.

+  // speculatively spawn a new renderer process if needed.

[nasko, 2014/12/10 23:11:34]

nit: s/spawn/create/

[carlosk, 2014/12/16 01:53:48]

Done.

+  void BeginNavigation(const FrameHostMsg_BeginNavigation_Params& params,
+                       const CommonNavigationParams& common_params);
+
+  // PlzNavigate
+  // Called when a navigation is ready to commit, to select the RenderFrameHost

[nasko, 2014/12/10 23:11:34]

nit: no need for comma

[carlosk, 2014/12/16 01:53:48]

Done.

+  // that will commit it.
   RenderFrameHostImpl* GetFrameHostForNavigation(const GURL& url,
                                                  ui::PageTransition transition);
 
+  // PlzNavigate
+  // Cancels any state for any ongoing navigation.
+  void CleanUpNavigation();
+
  private:
+  friend class NavigatorTestWithBrowserSideNavigation;
   friend class RenderFrameHostManagerTest;
   friend class TestWebContents;
 
@@ -466,6 +481,16 @@ 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 speculative RenderFrameHost for an ongoing

[nasko, 2014/12/10 23:11:34]

nit: It will be nice to avoid using "speculative" twice in the same sentence,
makes it hard to read.

[carlosk, 2014/12/16 01:53:48]

Yeah, this was very bad Engrish. ;) I updated the whole comment and hopefully
it's better now.

+  // 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 +510,8 @@ 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 (not pending)
+  // RenderFrameHost to be the active one.
   void CommitPending();
 
   // Runs the unload handler in the old RenderFrameHost, after the new
@@ -566,6 +593,7 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
   // transitioning between two Web UI pages: the RFH won't be swapped, so the
   // pending pointer will be unused, but there will be a pending Web UI
   // associated with the navigation.
+  // Note: This is not used in PlzNavigate.
   scoped_ptr<RenderFrameHostImpl> pending_render_frame_host_;
 
   // If a pending request needs to be transferred to another process, this
@@ -600,6 +628,22 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
 
   NotificationRegistrar registrar_;
 
+  // PlzNavigate
+  // These members store a speculative RenderFrameHost and WebUI. They are
+  // created early in during a navigation so the renderer process can be started
+  // in parallel with it. This is purely an optimization and is not required for
+  // correct behavior. 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: PlzNavigate only uses speculative RenderFrameHosts and not pending
+  // ones.
+  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_;
+
   base::WeakPtrFactory<RenderFrameHostManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderFrameHostManager);