Force spontaneous draws into the SW path

content/browser/android/in_process/synchronous_compositor_output_surface.cc

Index: content/browser/android/in_process/synchronous_compositor_output_surface.cc
diff --git a/content/browser/android/in_process/synchronous_compositor_output_surface.cc b/content/browser/android/in_process/synchronous_compositor_output_surface.cc
index 38bf88b3283a41b11aa573dd5a8a3bc8608de40f..a9fcfb9aded0697ad3be40288326cd2f51e4f8ae 100644
--- a/content/browser/android/in_process/synchronous_compositor_output_surface.cc
+++ b/content/browser/android/in_process/synchronous_compositor_output_surface.cc
@@ -88,6 +88,7 @@ SynchronousCompositorOutputSurface::SynchronousCompositorOutputSurface(
           scoped_ptr<cc::SoftwareOutputDevice>(new SoftwareDevice(this))),
       routing_id_(routing_id),
       needs_begin_frame_(false),
+      invoking_composite_(false),
       did_swap_buffer_(false),
       current_sw_canvas_(NULL) {
   capabilities_.deferred_gl_initialization = true;
@@ -104,7 +105,11 @@ SynchronousCompositorOutputSurface::~SynchronousCompositorOutputSurface() {
 }
 
 bool SynchronousCompositorOutputSurface::ForcedDrawToSoftwareDevice() const {
-  return current_sw_canvas_ != NULL;
+  // |current_sw_canvas_| indicates we're in a DemandDrawSw call. In addition
+  // |invoking_composite_| == false indicates an attempt to draw outside of
+  // the synchronous compositor's control: force it into SW path and hence to
+  // the null canvas (and will log a warning there).
+  return current_sw_canvas_ != NULL || !invoking_composite_;
 }
 
 bool SynchronousCompositorOutputSurface::BindToClient(
@@ -218,6 +223,7 @@ bool SynchronousCompositorOutputSurface::DemandDrawSw(SkCanvas* canvas) {
 
 void SynchronousCompositorOutputSurface::InvokeComposite(
     gfx::Size damage_size) {
+  invoking_composite_ = true;

[boliu, 2013/06/21 22:40:14]

Use base::AutoReset?

[joth, 2013/06/21 23:02:14]

Done.

Nice! Thought that existed, but I was searching the code for a ScopedFlibble
class...

   did_swap_buffer_ = false;
   SetNeedsRedrawRect(gfx::Rect(damage_size));
   if (needs_begin_frame_)
@@ -225,6 +231,7 @@ void SynchronousCompositorOutputSurface::InvokeComposite(
 
   if (did_swap_buffer_)
     OnSwapBuffersComplete(NULL);
+  invoking_composite_ = false;
 }
 
 void SynchronousCompositorOutputSurface::PostCheckForRetroactiveBeginFrame() {