Don't copy the Graphics2D when binding a new one. This brings the

webkit/plugins/ppapi/ppapi_plugin_instance.cc

 // Copyright (c) 2011 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 "webkit/plugins/ppapi/ppapi_plugin_instance.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
@@ skipping 1367 matching lines @@
 
   if (graphics_2d) {
     // Refuse to bind if we're transitioning to fullscreen.
     if (fullscreen_container_ && !fullscreen_)
       return PP_FALSE;
     if (graphics_2d->instance() != this)
       return PP_FALSE;  // Can't bind other instance's contexts.
     if (!graphics_2d->BindToInstance(this))
       return PP_FALSE;  // Can't bind to more than one instance.
 
-    // See http://crbug.com/49403: this can be further optimized by keeping the
-    // old device around and painting from it.
-    if (bound_graphics_2d()) {
-      // Start the new image with the content of the old image until the plugin
-      // repaints.
-      // Use ImageDataAutoMapper to ensure the image data is valid.
-      ImageDataAutoMapper mapper(bound_graphics_2d()->image_data());
-      if (!mapper.is_valid())
-        return PP_FALSE;
-      const SkBitmap* old_backing_bitmap =
-          bound_graphics_2d()->image_data()->GetMappedBitmap();
-      SkRect old_size = SkRect::MakeWH(
-          SkScalar(static_cast<float>(old_backing_bitmap->width())),
-          SkScalar(static_cast<float>(old_backing_bitmap->height())));
-
-      SkCanvas canvas(*graphics_2d->image_data()->GetMappedBitmap());
-      canvas.drawBitmap(*old_backing_bitmap, 0, 0);
-
-      // Fill in any extra space with white.
-      canvas.clipRect(old_size, SkRegion::kDifference_Op);
-      canvas.drawARGB(255, 255, 255, 255);
-    }
-
     bound_graphics_ = graphics_2d;
     setBackingTextureId(0);
     // BindToInstance will have invalidated the plugin if necessary.
   } else if (graphics_3d) {
     // Refuse to bind if we're transitioning to fullscreen.
     if (fullscreen_container_ && !fullscreen_)
       return PP_FALSE;
     // Make sure graphics can only be bound to the instance it is
     // associated with.
     if (graphics_3d->instance() != this)
@@ skipping 83 matching lines @@
 }
 
 PP_Bool PluginInstance::GetScreenSize(PP_Instance instance, PP_Size* size) {
   gfx::Size screen_size = delegate()->GetScreenSize();
   *size = PP_MakeSize(screen_size.width(), screen_size.height());
   return PP_TRUE;
 }
 
 }  // namespace ppapi
 }  // namespace webkit