Revert of cc: Remove use of PassAs() and constructor-casting with scoped_ptr.

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 89 matching lines @@
 }
 
 void SoftwareRenderer::BeginDrawingFrame(DrawingFrame* frame) {
   TRACE_EVENT0("cc", "SoftwareRenderer::BeginDrawingFrame");
   root_canvas_ = output_device_->BeginPaint(
       gfx::ToEnclosingRect(frame->root_damage_rect));
 }
 
 void SoftwareRenderer::FinishDrawingFrame(DrawingFrame* frame) {
   TRACE_EVENT0("cc", "SoftwareRenderer::FinishDrawingFrame");
-  current_framebuffer_lock_ = nullptr;
+  current_framebuffer_lock_.reset();
   current_canvas_ = NULL;
   root_canvas_ = NULL;
 
   current_frame_data_.reset(new SoftwareFrameData);
   output_device_->EndPaint(current_frame_data_.get());
 }
 
 void SoftwareRenderer::SwapBuffers(const CompositorFrameMetadata& metadata) {
   TRACE_EVENT0("cc,benchmark", "SoftwareRenderer::SwapBuffers");
   CompositorFrame compositor_frame;
@@ skipping 22 matching lines @@
   // the viewport's dimensions.
   is_scissor_enabled_ = false;
   SkISize size = current_canvas_->getDeviceSize();
   SetClipRect(gfx::Rect(size.width(), size.height()));
 }
 
 void SoftwareRenderer::Finish() {}
 
 void SoftwareRenderer::BindFramebufferToOutputSurface(DrawingFrame* frame) {
   DCHECK(!output_surface_->HasExternalStencilTest());
-  current_framebuffer_lock_ = nullptr;
+  current_framebuffer_lock_.reset();
   current_canvas_ = root_canvas_;
 }
 
 bool SoftwareRenderer::BindFramebufferToTexture(
     DrawingFrame* frame,
     const ScopedResource* texture,
     const gfx::Rect& target_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();
   InitializeViewport(frame,
                      target_rect,
                      gfx::Rect(target_rect.size()),
                      target_rect.size());
   return true;
 }
@@ skipping 427 matching lines @@
 }
 
 void SoftwareRenderer::DidChangeVisibility() {
   if (visible())
     EnsureBackbuffer();
   else
     DiscardBackbuffer();
 }
 
 }  // namespace cc