Remove PluginLoadObserver and related logic, it was only used for NPAPI.

content/child/plugin_messages.h

Index: content/child/plugin_messages.h
diff --git a/content/child/plugin_messages.h b/content/child/plugin_messages.h
index 25d4545f683a7411865d360a38eca5f0b233ddf9..c18da0a5f4b6cd9c2e4e8516cbf9fa349d73486e 100644
--- a/content/child/plugin_messages.h
+++ b/content/child/plugin_messages.h
@@ -39,7 +39,6 @@ IPC_STRUCT_BEGIN(PluginHostMsg_URLRequest_Params)
   IPC_STRUCT_MEMBER(std::string, method)
   IPC_STRUCT_MEMBER(std::string, target)
   IPC_STRUCT_MEMBER(std::vector<char>, buffer)
-  IPC_STRUCT_MEMBER(int, notify_id)
   IPC_STRUCT_MEMBER(bool, popups_allowed)
   IPC_STRUCT_MEMBER(bool, notify_redirects)
 IPC_STRUCT_END()
@@ -55,7 +54,6 @@ IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(PluginMsg_FetchURL_Params)
   IPC_STRUCT_MEMBER(unsigned long, resource_id)
-  IPC_STRUCT_MEMBER(int, notify_id)
   IPC_STRUCT_MEMBER(GURL, url)
   IPC_STRUCT_MEMBER(GURL, first_party_for_cookies)
   IPC_STRUCT_MEMBER(std::string, method)
@@ -116,11 +114,6 @@ IPC_SYNC_MESSAGE_ROUTED0_2(PluginMsg_GetFormValue,
                            base::string16 /* value */,
                            bool /* success */)
 
-IPC_MESSAGE_ROUTED3(PluginMsg_DidFinishLoadWithReason,
-                    GURL /* url */,
-                    int /* reason */,
-                    int /* notify_id */)
-
 // Updates the plugin location.
 IPC_MESSAGE_ROUTED1(PluginMsg_UpdateGeometry,
                     PluginMsg_UpdateGeometry_Param)
@@ -159,11 +152,10 @@ IPC_MESSAGE_ROUTED1(PluginMsg_DidFinishLoading,
 IPC_MESSAGE_ROUTED1(PluginMsg_DidFail,
                     unsigned long /* id */)
 
-IPC_MESSAGE_ROUTED4(PluginMsg_SendJavaScriptStream,
+IPC_MESSAGE_ROUTED3(PluginMsg_SendJavaScriptStream,
                     GURL /* url */,
                     std::string /* result */,
-                    bool /* success */,
-                    int /* notify_id */)
+                    bool /* success */)
 
 IPC_MESSAGE_ROUTED2(PluginMsg_DidReceiveManualResponse,
                     GURL /* url */,
@@ -176,10 +168,9 @@ IPC_MESSAGE_ROUTED0(PluginMsg_DidFinishManualLoading)
 
 IPC_MESSAGE_ROUTED0(PluginMsg_DidManualLoadFail)
 
-IPC_MESSAGE_ROUTED3(PluginMsg_HandleURLRequestReply,
+IPC_MESSAGE_ROUTED2(PluginMsg_HandleURLRequestReply,
                     unsigned long /* resource_id */,
-                    GURL /* url */,
-                    int /* notify_id */)
+                    GURL /* url */)
 
 IPC_MESSAGE_ROUTED2(PluginMsg_HTTPRangeRequestReply,
                     unsigned long /* resource_id */,