Make PrerenderHandle an observer of PrerenderContents.

chrome/renderer/prerender/prerender_dispatcher.cc

Index: chrome/renderer/prerender/prerender_dispatcher.cc
diff --git a/chrome/renderer/prerender/prerender_dispatcher.cc b/chrome/renderer/prerender/prerender_dispatcher.cc
index a3f72ec5798c2a26acdfbeb7a92d96bb2664a472..563efbc2d6e2828a7260004155375b4d5ba6c8ff 100644
--- a/chrome/renderer/prerender/prerender_dispatcher.cc
+++ b/chrome/renderer/prerender/prerender_dispatcher.cc
@@ -4,58 +4,80 @@
 
 #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) {

[mmenke, 2012/12/13 18:27:16]

Since we have it on stop, too, may want a:

DCHECK_NE(0u, prerenders_.count(prerender_id));

Think DCHECKing closer to the problem area is generally a good idea.

[gavinp, 2012/12/13 20:45:34]

Done.

+  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));

[mmenke, 2012/12/13 18:27:16]

	
(Draft) 2012/12/13 17:03:52
optional:  Think it's cleaner to use operator[] instead of insert here. 
[multi]map::insert just isn't used much in Chrome, probably because it's less
intuitive, ugly, and uses twice the code.

[gavinp, 2012/12/13 20:45:34]

Multimap has no subscript operator.

[mmenke, 2012/12/13 21:39:42]

Erm...  Good point.  I'd thought I'd seen prettier insertions, but probably was
just because of typedefs.

+}
+
+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));

[mmenke, 2012/12/13 18:27:16]

optional:  Think it's cleaner to use operator[] instead of insert here. 
[multi]map::insert just isn't used much in Chrome, probably because it's less
intuitive, ugly, and uses twice the code.

[gavinp, 2012/12/13 20:45:34]

Done.

 }
 
-void PrerenderDispatcher::OnRemovePrerenderURL(const GURL& url) {
-  PrerenderMap::iterator it = prerender_urls_.find(url);
-  // This is possible with a spurious remove.
+void PrerenderDispatcher::OnPrerenderStop(int prerender_id) {
+  DCHECK_NE(0u, prerenders_.count(prerender_id));
+
   // 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);

[mmenke, 2012/12/13 18:27:16]

Think it would be a little simpler to have only one while loop here.

[gavinp, 2012/12/13 20:51:24]

Done.

+  }
+  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()
 
@@ -65,6 +87,9 @@ bool PrerenderDispatcher::OnControlMessageReceived(
 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()));

[mmenke, 2012/12/13 18:27:16]

optional:  Think it's cleaner to use operator[] instead of insert here.

[gavinp, 2012/12/13 20:45:34]

Done.

+
   content::RenderThread::Get()->Send(new PrerenderHostMsg_AddLinkRelPrerender(
       extra_data.prerender_id(), GURL(prerender.url()),
       content::Referrer(GURL(prerender.referrer()), prerender.referrerPolicy()),