Linux: Fix some NULL versus 0 issues to appease gcc-4.5.

chrome/gpu/gpu_channel.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "chrome/gpu/gpu_channel.h"
 
@@ skipping 87 matching lines @@
   static int last_id = 0;
   return ++last_id;
 }
 
 void GpuChannel::OnCreateViewCommandBuffer(gfx::NativeViewId view_id,
                                            int32* route_id) {
   *route_id = 0;
 
 #if defined(ENABLE_GPU)
 
-  gfx::PluginWindowHandle handle = NULL;
+  gfx::PluginWindowHandle handle = gfx::kNullPluginWindow;
 #if defined(OS_WIN)
   gfx::NativeView view = gfx::NativeViewFromId(view_id);
 
   // Check that the calling renderer is allowed to render to this window.
   // TODO(apatrick): consider killing the renderer process rather than failing.
   int view_renderer_id = reinterpret_cast<int>(
       GetProp(view, chrome::kChromiumRendererIdProperty));
   if (view_renderer_id != renderer_id_)
     return;
   handle = view;
@@ skipping 25 matching lines @@
                                                 uint32 parent_texture_id,
                                                 int32* route_id) {
 #if defined(ENABLE_GPU)
   *route_id = GenerateRouteID();
   GpuCommandBufferStub* parent_stub = NULL;
   if (parent_route_id != 0)
     parent_stub = stubs_.Lookup(parent_route_id);
 
   scoped_ptr<GpuCommandBufferStub> stub(new GpuCommandBufferStub(
       this,
-      NULL,
+      gfx::kNullPluginWindow,
       parent_stub,
       size,
       parent_texture_id,
       *route_id));
   router_.AddRoute(*route_id, stub.get());
   stubs_.AddWithID(stub.release(), *route_id);
 #else
   *route_id = 0;
 #endif
 }
@@ skipping 24 matching lines @@
   channel_.reset(new IPC::SyncChannel(
       channel_name, IPC::Channel::MODE_SERVER, this, NULL,
       ChildProcess::current()->io_message_loop(), false,
       ChildProcess::current()->GetShutDownEvent()));
   return true;
 }
 
 std::string GpuChannel::GetChannelName() {
   return StringPrintf("%d.r%d", base::GetCurrentProcId(), renderer_id_);
 }