diff --git a/atom/browser/web_view_manager.cc b/atom/browser/web_view_manager.cc
index d57d0c84adf7..90d51e93e41a 100644
--- a/atom/browser/web_view_manager.cc
+++ b/atom/browser/web_view_manager.cc
@@ -7,11 +7,8 @@
 #include "atom/browser/api/atom_api_web_contents.h"
 #include "atom/browser/atom_browser_context.h"
 #include "atom/common/native_mate_converters/gurl_converter.h"
-#include "base/bind.h"
-#include "base/stl_util.h"
 #include "content/public/browser/render_process_host.h"
 #include "native_mate/dictionary.h"
-#include "native_mate/object_template_builder.h"
 #include "net/base/filename_util.h"
 
 #include "atom/common/node_includes.h"
@@ -82,7 +79,7 @@ void WebViewManager::AddGuest(int guest_instance_id,
                               content::WebContents* web_contents,
                               WebViewInfo info) {
   base::AutoLock auto_lock(lock_);
-  web_contents_map_[guest_instance_id] = { web_contents, embedder };
+  web_contents_embdder_map_[guest_instance_id] = { web_contents, embedder };
 
   int guest_process_id = web_contents->GetRenderProcessHost()->GetID();
   info.guest_instance_id = guest_instance_id;
@@ -96,12 +93,11 @@ void WebViewManager::AddGuest(int guest_instance_id,
 
 void WebViewManager::RemoveGuest(int guest_instance_id) {
   base::AutoLock auto_lock(lock_);
-  if (!ContainsKey(web_contents_map_, guest_instance_id)) {
+  if (!ContainsKey(web_contents_embdder_map_, guest_instance_id))
     return;
-  }
 
-  auto web_contents = web_contents_map_[guest_instance_id].web_contents;
-  web_contents_map_.erase(guest_instance_id);
+  auto web_contents = web_contents_embdder_map_[guest_instance_id].web_contents;
+  web_contents_embdder_map_.erase(guest_instance_id);
 
   int guest_process_id = web_contents->GetRenderProcessHost()->GetID();
   webview_info_map_.erase(guest_process_id);
@@ -132,15 +128,15 @@ content::WebContents* WebViewManager::GetGuestByInstanceID(
     return nullptr;
 
   int guest_instance_id = element_instance_id_to_guest_map_[key];
-  if (ContainsKey(web_contents_map_, guest_instance_id))
-    return web_contents_map_[guest_instance_id].web_contents;
+  if (ContainsKey(web_contents_embdder_map_, guest_instance_id))
+    return web_contents_embdder_map_[guest_instance_id].web_contents;
   else
     return nullptr;
 }
 
 bool WebViewManager::ForEachGuest(content::WebContents* embedder_web_contents,
                                   const GuestCallback& callback) {
-  for (auto& item : web_contents_map_)
+  for (auto& item : web_contents_embdder_map_)
     if (item.second.embedder == embedder_web_contents &&
         callback.Run(item.second.web_contents))
       return true;
diff --git a/atom/browser/web_view_manager.h b/atom/browser/web_view_manager.h
index 2f5d8a650d55..ad7d1e4cb291 100644
--- a/atom/browser/web_view_manager.h
+++ b/atom/browser/web_view_manager.h
@@ -10,7 +10,6 @@
 #include "base/files/file_path.h"
 #include "base/synchronization/lock.h"
 #include "content/public/browser/browser_plugin_guest_manager.h"
-#include "url/gurl.h"
 
 namespace content {
 class BrowserContext;
@@ -59,19 +58,16 @@ class WebViewManager : public content::BrowserPluginGuestManager {
 
  private:
   struct WebContentsWithEmbedder {
-    content::WebContents* web_contents;  // Weak ref.
+    content::WebContents* web_contents;
     content::WebContents* embedder;
   };
-  std::map<int, WebContentsWithEmbedder> web_contents_map_;
+  // guest_instance_id => (web_contents, embedder)
+  std::map<int, WebContentsWithEmbedder> web_contents_embdder_map_;
 
   struct ElementInstanceKey {
     content::WebContents* owner_web_contents;
     int element_instance_id;
 
-    ElementInstanceKey()
-        : owner_web_contents(nullptr),
-          element_instance_id(0) {}
-
     ElementInstanceKey(content::WebContents* owner_web_contents,
                        int element_instance_id)
         : owner_web_contents(owner_web_contents),
@@ -88,9 +84,11 @@ class WebViewManager : public content::BrowserPluginGuestManager {
           (element_instance_id == other.element_instance_id);
     }
   };
+  // (web_contents, element_instance_id) => guest_instance_id
   std::map<ElementInstanceKey, int> element_instance_id_to_guest_map_;
 
   typedef std::map<int, WebViewInfo> WebViewInfoMap;
+  // guest_process_id => (guest_instance_id, embedder, ...)
   WebViewInfoMap webview_info_map_;
 
   base::Lock lock_;