Keep event page alive when there's some Pepper plugin on it.

extensions/browser/extension_web_contents_observer.cc

 // Copyright 2014 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 "extensions/browser/extension_web_contents_observer.h"
 
 #include "content/public/browser/child_process_security_policy.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/url_constants.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/mojo/service_registration.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/browser/view_type_utils.h"
 #include "extensions/common/constants.h"
+#include "extensions/common/extension.h"
 #include "extensions/common/extension_messages.h"
 
 namespace extensions {
 namespace {
 
 const Extension* GetExtensionForRenderFrame(
     content::RenderFrameHost* render_frame_host) {
   content::SiteInstance* site_instance = render_frame_host->GetSiteInstance();
   GURL url = render_frame_host->GetLastCommittedURL();
   if (!url.is_empty()) {
@@ skipping 118 matching lines @@
 }
 
 void ExtensionWebContentsObserver::NotifyRenderViewType(
     content::RenderViewHost* render_view_host) {
   if (render_view_host) {
     render_view_host->Send(new ExtensionMsg_NotifyRenderViewType(
         render_view_host->GetRoutingID(), GetViewType(web_contents())));
   }
 }
 
+void ExtensionWebContentsObserver::PepperInstanceCreated() {
+  ProcessManager* const process_manager = ProcessManager::Get(browser_context_);
+  const Extension* const extension =

[not at google - send to devlin, 2015/05/26 21:18:42]

Kinda overboard-ing the "const" here IMO, but whatever you like.

+      process_manager->GetExtensionForWebContents(web_contents());
+  if (extension)
+    process_manager->IncrementLazyKeepaliveCount(extension);
+}
+
+void ExtensionWebContentsObserver::PepperInstanceDeleted() {
+  ProcessManager* const process_manager = ProcessManager::Get(browser_context_);
+  const Extension* const extension =
+      process_manager->GetExtensionForWebContents(web_contents());
+  if (extension)
+    process_manager->DecrementLazyKeepaliveCount(extension);
+}
+
 const Extension* ExtensionWebContentsObserver::GetExtension(
     content::RenderViewHost* render_view_host) {
   std::string extension_id = GetExtensionId(render_view_host);
   if (extension_id.empty())
     return NULL;
 
   // May be null if the extension doesn't exist, for example if somebody typos
   // a chrome-extension:// URL.
   return ExtensionRegistry::Get(browser_context_)
       ->GetExtensionById(extension_id, ExtensionRegistry::ENABLED);
 }
 
 // static
 std::string ExtensionWebContentsObserver::GetExtensionId(
     content::RenderViewHost* render_view_host) {
   // Note that due to ChromeContentBrowserClient::GetEffectiveURL(), hosted apps
   // (excluding bookmark apps) will have a chrome-extension:// URL for their
   // site, so we can ignore that wrinkle here.
   const GURL& site = render_view_host->GetSiteInstance()->GetSiteURL();
 
   if (!site.SchemeIs(kExtensionScheme))
     return std::string();
 
   return site.host();
 }
 
 }  // namespace extensions