Move Infobars core files to the Infobars component

chrome/browser/plugins/plugin_observer.h

Index: chrome/browser/plugins/plugin_observer.h
diff --git a/chrome/browser/plugins/plugin_observer.h b/chrome/browser/plugins/plugin_observer.h
index b0f43b77927e74c6414a9a826798a41bf73cd2b4..868eb3b0beb40eb46ba1aa61a3595c68e3b29459 100644
--- a/chrome/browser/plugins/plugin_observer.h
+++ b/chrome/browser/plugins/plugin_observer.h
@@ -15,7 +15,6 @@
 #endif
 
 class GURL;
-class InfoBarDelegate;
 class PluginFinder;
 class PluginMetadata;
 
@@ -28,6 +27,10 @@ namespace content {
 class WebContents;
 }
 
+namespace infobars {
+class InfoBarDelegate;
+}
+
 class PluginObserver : public content::WebContentsObserver,
                        public content::WebContentsUserData<PluginObserver> {
  public: