ui: Cleanup class/struct forward declarations

extensions/browser/extension_throttle_entry_interface.h

Index: extensions/browser/extension_throttle_entry_interface.h
diff --git a/extensions/browser/extension_throttle_entry_interface.h b/extensions/browser/extension_throttle_entry_interface.h
index 57d1b02c7dab9417e930c34a4825871d4027c621..0b52a0376772a2e7e4313c222c5e34f4c9da85c9 100644
--- a/extensions/browser/extension_throttle_entry_interface.h
+++ b/extensions/browser/extension_throttle_entry_interface.h
@@ -60,8 +60,8 @@ class ExtensionThrottleEntryInterface
   // indicated is already one of those that will be counted as an error.
   virtual void ReceivedContentWasMalformed(int response_code) = 0;
 
-  // Get the URL ID associated with his entry. Should only be used for debugging
-  // purpose.
+  // Get the URL ID associated with this entry. Should only be used for
+  // debugging purpose.
   virtual const std::string& GetURLIdForDebugging() const = 0;
 
  protected: