Update from https://crrev.com/305340

cc/output/software_renderer.cc

Index: cc/output/software_renderer.cc
diff --git a/cc/output/software_renderer.cc b/cc/output/software_renderer.cc
index 442cd8d5aea01c8ea12a18bb3bcb09d5f8d68161..ddd3473ad34a1c114cd47a6d3185cab1accf3400 100644
--- a/cc/output/software_renderer.cc
+++ b/cc/output/software_renderer.cc
@@ -63,7 +63,7 @@ static SkShader::TileMode WrapModeToTileMode(GLint wrap_mode) {
 
 scoped_ptr<SoftwareRenderer> SoftwareRenderer::Create(
     RendererClient* client,
-    const LayerTreeSettings* settings,
+    const RendererSettings* settings,
     OutputSurface* output_surface,
     ResourceProvider* resource_provider) {
   return make_scoped_ptr(new SoftwareRenderer(
@@ -71,7 +71,7 @@ scoped_ptr<SoftwareRenderer> SoftwareRenderer::Create(
 }
 
 SoftwareRenderer::SoftwareRenderer(RendererClient* client,
-                                   const LayerTreeSettings* settings,
+                                   const RendererSettings* settings,
                                    OutputSurface* output_surface,
                                    ResourceProvider* resource_provider)
     : DirectRenderer(client, settings, output_surface, resource_provider),
@@ -108,6 +108,7 @@ void SoftwareRenderer::BeginDrawingFrame(DrawingFrame* frame) {
 void SoftwareRenderer::FinishDrawingFrame(DrawingFrame* frame) {
   TRACE_EVENT0("cc", "SoftwareRenderer::FinishDrawingFrame");
   current_framebuffer_lock_ = nullptr;
+  current_framebuffer_canvas_.clear();
   current_canvas_ = NULL;
   root_canvas_ = NULL;
 
@@ -151,6 +152,7 @@ void SoftwareRenderer::Finish() {}
 void SoftwareRenderer::BindFramebufferToOutputSurface(DrawingFrame* frame) {
   DCHECK(!output_surface_->HasExternalStencilTest());
   current_framebuffer_lock_ = nullptr;
+  current_framebuffer_canvas_.clear();
   current_canvas_ = root_canvas_;
 }
 
@@ -161,7 +163,9 @@ bool SoftwareRenderer::BindFramebufferToTexture(
   current_framebuffer_lock_ = make_scoped_ptr(
       new ResourceProvider::ScopedWriteLockSoftware(
           resource_provider_, texture->id()));
-  current_canvas_ = current_framebuffer_lock_->sk_canvas();
+  current_framebuffer_canvas_ =
+      skia::AdoptRef(new SkCanvas(current_framebuffer_lock_->sk_bitmap()));
+  current_canvas_ = current_framebuffer_canvas_.get();
   InitializeViewport(frame,
                      target_rect,
                      gfx::Rect(target_rect.size()),