Call OnSwapBuffersComplete at the end of each frame

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 d5876e41a3ef8d7ab4a7002a001daff9553cd45a..6a4f7cfe2a470c1ce79ccc7a7864f01316cc91aa 100644
--- a/content/browser/android/in_process/synchronous_compositor_output_surface.cc
+++ b/content/browser/android/in_process/synchronous_compositor_output_surface.cc
@@ -62,12 +62,16 @@ class SynchronousCompositorOutputSurface::SoftwareDevice
   }
   virtual SkCanvas* BeginPaint(gfx::Rect damage_rect) OVERRIDE {
     DCHECK(surface_->current_sw_canvas_);
-    if (surface_->current_sw_canvas_)
-      return surface_->current_sw_canvas_;
-    return &null_canvas_;
+    if (!surface_->current_sw_canvas_) {
+      LOG(WARNING) << "BeginPaint with no canvas set";
+      return &null_canvas_;
+    }
+    LOG_IF(WARNING, surface_->did_swap_buffer_)
+        << "Mutliple calls to BeginPaint per frame";
+    return surface_->current_sw_canvas_;
   }
   virtual void EndPaint(cc::SoftwareFrameData* frame_data) OVERRIDE {
-    surface_->current_sw_canvas_ = NULL;
+    surface_->did_swap_buffer_ = true;
   }
   virtual void CopyToBitmap(gfx::Rect rect, SkBitmap* output) OVERRIDE {
     NOTIMPLEMENTED();
@@ -173,9 +177,8 @@ bool SynchronousCompositorOutputSurface::DemandDrawSw(SkCanvas* canvas) {
 
   InvokeComposite(transform, damage_area);
 
-  bool finished_draw = current_sw_canvas_ == NULL;
   current_sw_canvas_ = NULL;
-  return finished_draw;
+  return did_swap_buffer_;
 }
 
 bool SynchronousCompositorOutputSurface::DemandDrawHw(
@@ -194,7 +197,6 @@ bool SynchronousCompositorOutputSurface::DemandDrawHw(
   if (current_context)
     current_context->ReleaseCurrent(NULL);
 
-  did_swap_buffer_ = false;
 
   InvokeComposite(transform, damage_area);
 
@@ -204,11 +206,15 @@ bool SynchronousCompositorOutputSurface::DemandDrawHw(
 void SynchronousCompositorOutputSurface::InvokeComposite(
     const gfx::Transform& transform,
     gfx::Rect damage_area) {
+  did_swap_buffer_ = false;
   // TODO(boliu): This assumes |transform| is identity and |damage_area| is the
   // whole view. Tracking bug to implement this: crbug.com/230463.
   client_->SetNeedsRedrawRect(damage_area);
   if (needs_begin_frame_)
     client_->BeginFrame(base::TimeTicks::Now());
+
+  if (did_swap_buffer_)
+    client_->OnSwapBuffersComplete();

[no sievers, 2013/06/05 21:08:05]

Is it even more straightforward to call this from SwapBuffers() (or maybe post a
task from there)?

[joth, 2013/06/05 21:26:40]

SwapBuffers() isn't called in the SW draw case.

 }
 
 // Not using base::NonThreadSafe as we want to enforce a more exacting threading