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

extensions/browser/extension_web_contents_observer.cc

Index: extensions/browser/extension_web_contents_observer.cc
diff --git a/extensions/browser/extension_web_contents_observer.cc b/extensions/browser/extension_web_contents_observer.cc
index 5ba2ebb5fcf81f9d3306e921877d52012bb3d44c..04335a527b8531cb9c7e3aac456528117b7be9ad 100644
--- a/extensions/browser/extension_web_contents_observer.cc
+++ b/extensions/browser/extension_web_contents_observer.cc
@@ -18,6 +18,7 @@
 #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 {
@@ -156,6 +157,22 @@ void ExtensionWebContentsObserver::NotifyRenderViewType(
   }
 }
 
+void ExtensionWebContentsObserver::PepperInstanceCreated() {
+  ProcessManager* const process_manager = ProcessManager::Get(browser_context_);
+  const Extension* const extension =
+      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);