PPAPI: Fix GetBrowserInterface race conditions

ppapi/proxy/interface_list.h

 // Copyright (c) 2012 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.
 
 #ifndef PPAPI_PROXY_INTERFACE_LIST_H_
 #define PPAPI_PROXY_INTERFACE_LIST_H_
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "base/synchronization/lock.h"
 #include "ppapi/proxy/interface_proxy.h"
 #include "ppapi/proxy/ppapi_proxy_export.h"
 #include "ppapi/shared_impl/ppapi_permissions.h"
 
 namespace ppapi {
 namespace proxy {
 
 class PPAPI_PROXY_EXPORT InterfaceList {
  public:
   InterfaceList();
@@ skipping 18 matching lines @@
   InterfaceProxy::Factory GetFactoryForID(ApiID id) const;
 
   // Returns the interface pointer for the given browser or plugin interface,
   // or NULL if it's not supported.
   const void* GetInterfaceForPPB(const std::string& name);
   const void* GetInterfaceForPPP(const std::string& name) const;
 
  private:
   friend class InterfaceListTest;
 
-  struct InterfaceInfo {
-    InterfaceInfo()
-        : iface(NULL),
-          required_permission(PERMISSION_NONE),
-          interface_logged(false) {
-    }
+  class InterfaceInfo {
+   public:
     InterfaceInfo(const void* in_interface, Permission in_perm)
-        : iface(in_interface),
-          required_permission(in_perm),
-          interface_logged(false) {
+        : iface_(in_interface),
+          required_permission_(in_perm),
+          sent_to_uma_(false) {
     }
 
-    const void* iface;
+    const void* iface() { return iface_; }
 
     // Permission required to return non-null for this interface. This will
     // be checked with the value set via SetProcessGlobalPermissionBits when
     // an interface is requested.
-    Permission required_permission;
+    Permission required_permission() { return required_permission_; };
 
-    // Interface usage is logged just once per-interface-per-plugin-process.
-    bool interface_logged;
+    // Call this any time the interface is requested. It will log a UMA count
+    // only the first time. This is safe to call from any thread, regardless of
+    // whether the proxy lock is held.
+    void LogWithUmaOnce(IPC::Sender* sender, const std::string& name);
+   private:
+    DISALLOW_COPY_AND_ASSIGN(InterfaceInfo);
+
+    const void* const iface_;
+    const Permission required_permission_;
+
+    bool sent_to_uma_;
+    base::Lock sent_to_uma_lock_;
   };
+  // Give friendship for HashInterfaceName.
+  friend class InterfaceInfo;
 
-  typedef std::map<std::string, InterfaceInfo> NameToInterfaceInfoMap;
+  typedef base::ScopedPtrHashMap<std::string, InterfaceInfo>
+      NameToInterfaceInfoMap;
 
   void AddProxy(ApiID id, InterfaceProxy::Factory factory);
 
   // Permissions is the type of permission required to access the corresponding
   // interface. Currently this must be just one unique permission (rather than
   // a bitfield).
   void AddPPB(const char* name, const void* iface, Permission permission);
   void AddPPP(const char* name, const void* iface);
 
   // Hash the interface name for UMA logging.
   static int HashInterfaceName(const std::string& name);
 
   PpapiPermissions permissions_;
 
   NameToInterfaceInfoMap name_to_browser_info_;
   NameToInterfaceInfoMap name_to_plugin_info_;
 
   InterfaceProxy::Factory id_to_factory_[API_ID_COUNT];
 
   DISALLOW_COPY_AND_ASSIGN(InterfaceList);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_INTERFACE_LIST_H_