Linux: fix a bunch of NULL vs. 0 issues spotted by gcc 4.5.

chrome/renderer/pepper_plugin_delegate_impl.cc

Index: chrome/renderer/pepper_plugin_delegate_impl.cc
diff --git a/chrome/renderer/pepper_plugin_delegate_impl.cc b/chrome/renderer/pepper_plugin_delegate_impl.cc
index eba798aab2259889715af719b6a00432a3c634b0..28bf02b8b40640b14dde4e6f5045800e1e53035a 100644
--- a/chrome/renderer/pepper_plugin_delegate_impl.cc
+++ b/chrome/renderer/pepper_plugin_delegate_impl.cc
@@ -384,7 +384,7 @@ PepperPluginDelegateImpl::CreatePepperPlugin(const FilePath& path) {
     return module;  // Return the NULL module.
 
   // Out of process: have the browser start the plugin process for us.
-  base::ProcessHandle plugin_process_handle = NULL;
+  base::ProcessHandle plugin_process_handle = base::kNullProcessHandle;
   IPC::ChannelHandle channel_handle;
   render_view_->Send(new ViewHostMsg_OpenChannelToPepperPlugin(
       path, &plugin_process_handle, &channel_handle));