Make PrerenderHandle an observer of PrerenderContents.

chrome/renderer/prerender/prerender_dispatcher.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/prerender/prerender_dispatcher.h"
 
+#include <stack>
+
 #include "base/logging.h"
 #include "chrome/common/prerender_messages.h"
 #include "chrome/renderer/prerender/prerender_extra_data.h"
+#include "content/public/common/referrer.h"
 #include "content/public/renderer/render_thread.h"
+#include "content/public/renderer/render_view.h"
 #include "googleurl/src/gurl.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebPrerenderingSupport.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebString.h"
+#include "third_party/WebKit/Source/Platform/chromium/public/WebURL.h"
 
 namespace prerender {
 
+using WebKit::WebPrerender;
+using WebKit::WebPrerenderingSupport;
+
 PrerenderDispatcher::PrerenderDispatcher() {
-  WebKit::WebPrerenderingSupport::initialize(this);
+  WebPrerenderingSupport::initialize(this);
 }
 
 PrerenderDispatcher::~PrerenderDispatcher() {
-  WebKit::WebPrerenderingSupport::shutdown();
+  WebPrerenderingSupport::shutdown();
 }
 
 bool PrerenderDispatcher::IsPrerenderURL(const GURL& url) const {
-  return prerender_urls_.find(url) != prerender_urls_.end();
+  return running_prerender_urls_.count(url) >= 1;
 }
 
-void PrerenderDispatcher::OnAddPrerenderURL(const GURL& url) {
-  PrerenderMap::iterator it = prerender_urls_.find(url);
-  if (it != prerender_urls_.end()) {
-    DCHECK_LT(0, it->second);
-    it->second += 1;
-  } else {
-    prerender_urls_[url] = 1;
-  }
+void PrerenderDispatcher::OnPrerenderStart(int prerender_id) {
+  std::map<int, GURL>::iterator it = prerenders_.find(prerender_id);
+  if (it == prerenders_.end())
+    return;
+  const GURL& url = it->second;
+  running_prerender_urls_.insert(
+      std::multimap<GURL, int>::value_type(url, prerender_id));
 }
 
-void PrerenderDispatcher::OnRemovePrerenderURL(const GURL& url) {
-  PrerenderMap::iterator it = prerender_urls_.find(url);
-  // This is possible with a spurious remove.
+void PrerenderDispatcher::OnPrerenderAddAlias(int prerender_id,
+                                              const GURL& url) {
+  DCHECK_LT(0u, prerenders_.count(prerender_id));
+  running_prerender_urls_.insert(
+      std::multimap<GURL, int>::value_type(url, prerender_id));
+}
+
+void PrerenderDispatcher::OnPrerenderStop(int prerender_id) {
+  // It's possible we will receive a spurious remove, so we don't crash in that
+  // situation.

[mmenke, 2012/12/12 16:54:12]

Is this comment accurate?  We only delete prerenders from the list in response
to this message.

Not suggesting removing the check (yet, at least), just fixing the comment.

[gavinp, 2012/12/13 13:38:03]

Done.

+  if (prerenders_.count(prerender_id) == 0)
+    return;
+
   // TODO(cbentzel): We'd also want to send the map of active prerenders when
   // creating a new render process, so the Add/Remove go relative to that.
   // This may not be that big of a deal in practice, since the newly created tab
   // is unlikely to go to the prerendered page.
-  if (it == prerender_urls_.end())
-    return;
-  DCHECK_LT(0, it->second);
-  it->second -= 1;
-  if (it->second == 0)
-    prerender_urls_.erase(it);
+  prerenders_.erase(prerender_id);
+
+  std::stack<std::multimap<GURL, int>::iterator> to_delete;
+  for (std::multimap<GURL, int>::iterator it = running_prerender_urls_.begin();
+       it != running_prerender_urls_.end(); ++it) {
+    if (it->second == prerender_id)
+      to_delete.push(it);
+  }
+  while (!to_delete.empty()) {
+    running_prerender_urls_.erase(to_delete.top());
+    to_delete.pop();
+  }
 }
 
 bool PrerenderDispatcher::OnControlMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(PrerenderDispatcher, message)
-    IPC_MESSAGE_HANDLER(PrerenderMsg_AddPrerenderURL, OnAddPrerenderURL)
-    IPC_MESSAGE_HANDLER(PrerenderMsg_RemovePrerenderURL, OnRemovePrerenderURL)
+    IPC_MESSAGE_HANDLER(PrerenderMsg_OnPrerenderStart, OnPrerenderStart)
+    IPC_MESSAGE_HANDLER(PrerenderMsg_OnPrerenderAddAlias, OnPrerenderAddAlias)
+    IPC_MESSAGE_HANDLER(PrerenderMsg_OnPrerenderStop, OnPrerenderStop)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
   return handled;
 }
 
 void PrerenderDispatcher::add(const WebKit::WebPrerender& prerender) {
   const PrerenderExtraData& extra_data =
       PrerenderExtraData::FromPrerender(prerender);
+  prerenders_.insert(std::map<int, GURL>::value_type(extra_data.prerender_id(),
+                                                     prerender.url()));
+
   content::RenderThread::Get()->Send(new PrerenderHostMsg_AddLinkRelPrerender(
       extra_data.prerender_id(), GURL(prerender.url()),
       content::Referrer(GURL(prerender.referrer()), prerender.referrerPolicy()),
       extra_data.size(), extra_data.render_view_route_id()));

[mmenke, 2012/12/12 16:54:12]

For future consideration:  Another leak case:  If a prerender is never started,
we just leak it into the prerenders_ list.  These aren't huge leaks, but still
think that fixing them should be given a fairly high priority, after landing
these CLs.

[gavinp, 2012/12/13 13:38:03]

Good point. I think it'd be good if we tightened up WebKit (which sends a lot of
redundant events), and got these different maps in strong longstep with each
other, and leak free.

 }
 
 void PrerenderDispatcher::cancel(const WebKit::WebPrerender& prerender) {
   const PrerenderExtraData& extra_data =
       PrerenderExtraData::FromPrerender(prerender);
   content::RenderThread::Get()->Send(
       new PrerenderHostMsg_CancelLinkRelPrerender(extra_data.prerender_id()));
 }
 
 void PrerenderDispatcher::abandon(const WebKit::WebPrerender& prerender) {
   const PrerenderExtraData& extra_data =
       PrerenderExtraData::FromPrerender(prerender);
   content::RenderThread::Get()->Send(
       new PrerenderHostMsg_AbandonLinkRelPrerender(extra_data.prerender_id()));
 }
 
 }  // namespace prerender