Revert of Fix event page process cleanup when running in --isolate-extensions mode.

extensions/browser/process_manager.cc

Index: extensions/browser/process_manager.cc
diff --git a/extensions/browser/process_manager.cc b/extensions/browser/process_manager.cc
index be623e39ac1449489c879e2337e5d9afdbb24cec..a71b4c9d89fdb29a9494bf4d2694316f60299a7f 100644
--- a/extensions/browser/process_manager.cc
+++ b/extensions/browser/process_manager.cc
@@ -569,37 +569,24 @@
     uint64_t request_id) {
   ExtensionHost* host = GetBackgroundHostForExtension(
       GetExtensionID(render_frame_host));
-  if (!host || !IsFrameInExtensionHost(host, render_frame_host))
-    return;
-
-  auto result =
-      pending_network_requests_.insert(std::make_pair(request_id, host));
+  auto result = pending_network_requests_.insert(request_id);
   DCHECK(result.second) << "Duplicate network request IDs.";
-
-  IncrementLazyKeepaliveCount(host->extension());
-  host->OnNetworkRequestStarted(request_id);
+  if (host && IsFrameInExtensionHost(host, render_frame_host)) {
+    IncrementLazyKeepaliveCount(host->extension());
+    host->OnNetworkRequestStarted(request_id);
+  }
 }
 
 void ProcessManager::OnNetworkRequestDone(
     content::RenderFrameHost* render_frame_host,
     uint64_t request_id) {
-  auto result = pending_network_requests_.find(request_id);
-  if (result == pending_network_requests_.end())
-    return;
-
-  // The cached |host| can be invalid, if it was deleted between the time it
-  // was inserted in the map and the look up. It is checked to ensure it is in
-  // the list of existing background_hosts_.
-  ExtensionHost* host = result->second;
-  pending_network_requests_.erase(result);
-
-  if (background_hosts_.find(host) == background_hosts_.end())
-    return;
-
-  DCHECK(IsFrameInExtensionHost(host, render_frame_host));
-
-  host->OnNetworkRequestDone(request_id);
-  DecrementLazyKeepaliveCount(host->extension());
+  ExtensionHost* host = GetBackgroundHostForExtension(
+      GetExtensionID(render_frame_host));
+  if (host && IsFrameInExtensionHost(host, render_frame_host)) {
+    host->OnNetworkRequestDone(request_id);
+    if (pending_network_requests_.erase(request_id))
+      DecrementLazyKeepaliveCount(host->extension());
+  }
 }
 
 void ProcessManager::CancelSuspend(const Extension* extension) {