[Extensions] Clean up the handling of ExtensionHostMsg_Request

extensions/browser/extensions_browser_client.h

Index: extensions/browser/extensions_browser_client.h
diff --git a/extensions/browser/extensions_browser_client.h b/extensions/browser/extensions_browser_client.h
index 49d00dbf197847f3a02ada86a5d8b89e2084b2d3..6e99f7fa4c51b7a770e4b6b48ce4d98037ea6fac 100644
--- a/extensions/browser/extensions_browser_client.h
+++ b/extensions/browser/extensions_browser_client.h
@@ -44,6 +44,7 @@ class ExtensionHostDelegate;
 class ExtensionPrefsObserver;
 class ExtensionSystem;
 class ExtensionSystemProvider;
+class ExtensionWebContentsObserver;
 class InfoMap;
 class ProcessManagerDelegate;
 class RuntimeAPIDelegate;
@@ -212,6 +213,10 @@ class ExtensionsBrowserClient {
   // is left up to the embedder.
   virtual bool IsMinBrowserVersionSupported(const std::string& min_version) = 0;
 
+  // Returns the ExtensionWebContentsObserver for the given |web_contents|.
+  virtual ExtensionWebContentsObserver* GetExtensionWebContentsObserver(
+      content::WebContents* web_contents) = 0;
+
   // Returns the single instance of |this|.
   static ExtensionsBrowserClient* Get();