cc: Fix readback from non-root layers.

cc/output/software_renderer.cc

 // Copyright 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 "cc/output/software_renderer.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 137 matching lines @@
 
 void SoftwareRenderer::BindFramebufferToOutputSurface(DrawingFrame* frame) {
   current_framebuffer_lock_.reset();
   current_canvas_ = root_canvas_;
 }
 
 bool SoftwareRenderer::BindFramebufferToTexture(
     DrawingFrame* frame,
     const ScopedResource* texture,
     gfx::Rect framebuffer_rect) {
+  current_framebuffer_lock_.reset();
   current_framebuffer_lock_ = make_scoped_ptr(
       new ResourceProvider::ScopedWriteLockSoftware(
           resource_provider_, texture->id()));
   current_canvas_ = current_framebuffer_lock_->sk_canvas();
   InitializeMatrices(frame, framebuffer_rect, false);
   SetDrawViewportSize(framebuffer_rect.size());
 
   return true;
 }
 
@@ skipping 259 matching lines @@
                              4 * rect.width());
 }
 
 void SoftwareRenderer::SetVisible(bool visible) {
   if (visible_ == visible)
     return;
   visible_ = visible;
 }
 
 }  // namespace cc