PPAPI: Fix GetBrowserInterface race conditions

ppapi/proxy/interface_list.h

Index: ppapi/proxy/interface_list.h
diff --git a/ppapi/proxy/interface_list.h b/ppapi/proxy/interface_list.h
index a2b4569c8f1b3b3693af6f85b068e82095a334c4..dc109e5c5afd45ca1395ff1dec3d658684e12bbf 100644
--- a/ppapi/proxy/interface_list.h
+++ b/ppapi/proxy/interface_list.h
@@ -9,6 +9,8 @@
 #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"
@@ -47,30 +49,39 @@ class PPAPI_PROXY_EXPORT InterfaceList {
  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_; };
+
+    // 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_;
 
-    // Interface usage is logged just once per-interface-per-plugin-process.
-    bool interface_logged;
+    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);