Don't overwrit image data case entries that are just marked usable.

ppapi/proxy/ppb_graphics_2d_proxy.cc

 // Copyright (c) 2012 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.
 
 #include "ppapi/proxy/ppb_graphics_2d_proxy.h"
 
 #include <string.h>  // For memset.
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/ppb_graphics_2d.h"
 #include "ppapi/proxy/enter_proxy.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
 #include "ppapi/proxy/plugin_resource_tracker.h"
 #include "ppapi/proxy/ppapi_messages.h"
+#include "ppapi/proxy/ppb_image_data_proxy.h"
 #include "ppapi/shared_impl/tracked_callback.h"
 #include "ppapi/thunk/enter.h"
 #include "ppapi/thunk/ppb_graphics_2d_api.h"
 #include "ppapi/thunk/thunk.h"
 
 using ppapi::thunk::PPB_Graphics2D_API;
 
 namespace ppapi {
 namespace proxy {
 
@@ skipping 84 matching lines @@
 void Graphics2D::Scroll(const PP_Rect* clip_rect,
                         const PP_Point* amount) {
   PP_Rect dummy;
   memset(&dummy, 0, sizeof(PP_Rect));
   GetDispatcher()->Send(new PpapiHostMsg_PPBGraphics2D_Scroll(
       kApiID, host_resource(), !!clip_rect, clip_rect ? *clip_rect : dummy,
       *amount));
 }
 
 void Graphics2D::ReplaceContents(PP_Resource image_data) {
-  Resource* image_object =
-      PpapiGlobals::Get()->GetResourceTracker()->GetResource(image_data);
-  if (!image_object || pp_instance() != image_object->pp_instance()) {
+  thunk::EnterResourceNoLock<thunk::PPB_ImageData_API> enter_image(
+      image_data, true);
+  if (enter_image.failed())
+    return;
+
+  ImageData* image_object = static_cast<ImageData*>(enter_image.object());
+  if (pp_instance() != image_object->pp_instance()) {
     Log(PP_LOGLEVEL_ERROR,
-        "PPB_Graphics2D.PaintImageData: Bad image resource.");
+        "PPB_Graphics2D.ReplaceContents: Image resource for another instance.");
     return;
   }
+  image_object->set_used_in_replace_contents();
 
   GetDispatcher()->Send(new PpapiHostMsg_PPBGraphics2D_ReplaceContents(
       kApiID, host_resource(), image_object->host_resource()));
 }
 
 bool Graphics2D::SetScale(float scale) {
   if (scale <= 0.0f)
     return false;
   GetDispatcher()->Send(new PpapiHostMsg_PPBGraphics2D_Dev_SetScale(
       kApiID, host_resource(), scale));
@@ skipping 154 matching lines @@
 
 void PPB_Graphics2D_Proxy::SendFlushACKToPlugin(
     int32_t result,
     const HostResource& graphics_2d) {
   dispatcher()->Send(new PpapiMsg_PPBGraphics2D_FlushACK(kApiID, graphics_2d,
                                                          result));
 }
 
 }  // namespace proxy
 }  // namespace ppapi