Draw the offscreen texture to reflector's surface without extra copy

content/browser/compositor/reflector_impl.cc

Index: content/browser/compositor/reflector_impl.cc
diff --git a/content/browser/compositor/reflector_impl.cc b/content/browser/compositor/reflector_impl.cc
index c58ee567640d107ab725888d5902e0f322e6c0ee..dcc0dc2bbe675af19151a929184a1353e7e00cb9 100644
--- a/content/browser/compositor/reflector_impl.cc
+++ b/content/browser/compositor/reflector_impl.cc
@@ -8,7 +8,7 @@
 #include "base/location.h"
 #include "content/browser/compositor/browser_compositor_output_surface.h"
 #include "content/browser/compositor/owned_mailbox.h"
-#include "content/common/gpu/client/gl_helper.h"
+//#include "content/common/gpu/client/gl_helper.h"
 #include "ui/compositor/layer.h"
 
 namespace content {
@@ -23,11 +23,11 @@ struct ReflectorImpl::LayerData {
 ReflectorImpl::ReflectorImpl(ui::Compositor* mirrored_compositor,
                              ui::Layer* mirroring_layer)
     : mirrored_compositor_(mirrored_compositor),
-      mirrored_compositor_gl_helper_texture_id_(0),
       flip_texture_(false),
+      composition_count_(0),
       output_surface_(nullptr) {
   if (mirroring_layer)
-    mirroring_layers_.push_back(new LayerData(mirroring_layer));
+    AddMirroringLayer(mirroring_layer);
 }
 
 ReflectorImpl::~ReflectorImpl() {
@@ -46,10 +46,6 @@ void ReflectorImpl::DetachFromOutputSurface() {
   DCHECK(mailbox_.get());
   mailbox_ = nullptr;
   output_surface_ = nullptr;
-  mirrored_compositor_gl_helper_->DeleteTexture(
-      mirrored_compositor_gl_helper_texture_id_);
-  mirrored_compositor_gl_helper_texture_id_ = 0;
-  mirrored_compositor_gl_helper_ = nullptr;
   for (LayerData* layer_data : mirroring_layers_)
     layer_data->layer->SetShowSolidColorContent();
 }
@@ -63,34 +59,13 @@ void ReflectorImpl::OnSourceSurfaceReady(
   if (output_surface_)
     DetachFromOutputSurface();
 
-  // Use the GLHelper from the ImageTransportFactory for our OwnedMailbox so we
-  // don't have to manage the lifetime of the GLHelper relative to the lifetime
-  // of the mailbox.
-  GLHelper* shared_helper = ImageTransportFactory::GetInstance()->GetGLHelper();
-  mailbox_ = new OwnedMailbox(shared_helper);
-  for (LayerData* layer_data : mirroring_layers_)
-    layer_data->needs_set_mailbox = true;
+  output_surface_ = output_surface;
 
-  // Create a GLHelper attached to the mirrored compositor's output surface for
-  // copying the output of the mirrored compositor.
-  mirrored_compositor_gl_helper_.reset(
-      new GLHelper(output_surface->context_provider()->ContextGL(),
-                   output_surface->context_provider()->ContextSupport()));
-  // Create a texture id in the name space of the new GLHelper to update the
-  // mailbox being held by the |mirroring_layer_|.
-  mirrored_compositor_gl_helper_texture_id_ =
-      mirrored_compositor_gl_helper_->ConsumeMailboxToTexture(
-          mailbox_->mailbox(), mailbox_->sync_point());
+  composition_started_callback_ =
+      output_surface_->CreateCompositionStartedCallback();
 
   flip_texture_ = !output_surface->capabilities().flipped_output_surface;
 
-  // The texture doesn't have the data. Request full redraw on mirrored
-  // compositor so that the full content will be copied to mirroring compositor.
-  // This full redraw should land us in OnSourceSwapBuffers() to resize the
-  // texture appropriately.
-  mirrored_compositor_->ScheduleFullRedraw();
-
-  output_surface_ = output_surface;
   output_surface_->SetReflector(this);
 }
 
@@ -100,58 +75,87 @@ void ReflectorImpl::OnMirroringCompositorResized() {
 }
 
 void ReflectorImpl::AddMirroringLayer(ui::Layer* layer) {
+  DCHECK(layer->GetCompositor());
   DCHECK(mirroring_layers_.end() == FindLayerData(layer));
+
   LayerData* layer_data = new LayerData(layer);
   if (mailbox_)
     layer_data->needs_set_mailbox = true;
   mirroring_layers_.push_back(layer_data);
   mirrored_compositor_->ScheduleFullRedraw();
+
+  layer->GetCompositor()->AddObserver(this);
 }
 
 void ReflectorImpl::RemoveMirroringLayer(ui::Layer* layer) {
+  DCHECK(layer->GetCompositor());
+
   ScopedVector<LayerData>::iterator iter = FindLayerData(layer);
   DCHECK(iter != mirroring_layers_.end());
   (*iter)->layer->SetShowSolidColorContent();
   mirroring_layers_.erase(iter);
 
+  layer->GetCompositor()->RemoveObserver(this);
+  composition_count_--;
+  if (composition_count_ == 0 && !composition_started_callback_.is_null())
+    composition_started_callback_.Run();
+
   if (mirroring_layers_.empty() && output_surface_)
     DetachFromOutputSurface();
 }
 
+void ReflectorImpl::OnCompositingStarted(ui::Compositor* compositor,
+                                         base::TimeTicks start_time) {
+  if (composition_count_ > 0 && --composition_count_ == 0 &&
+      !composition_started_callback_.is_null()) {
+    composition_started_callback_.Run();
+  }
+}
+
+void ReflectorImpl::OnSourceTextureMailboxUpdated(
+    scoped_refptr<OwnedMailbox> mailbox) {
+  mailbox_ = mailbox;
+  if (mailbox_.get()) {
+    for (LayerData* layer_data : mirroring_layers_)
+      layer_data->needs_set_mailbox = true;
+
+    // The texture doesn't have the data. Request full redraw on mirrored
+    // compositor so that the full content will be copied to mirroring
+    // compositor. This full redraw should land us in OnSourceSwapBuffers() to
+    // resize the texture appropriately.
+    mirrored_compositor_->ScheduleFullRedraw();
+  }
+}
+
 void ReflectorImpl::OnSourceSwapBuffers() {
-  if (mirroring_layers_.empty())
+  if (mirroring_layers_.empty()) {
+    if (!composition_started_callback_.is_null())
+      composition_started_callback_.Run();
     return;
+  }
+
   // Should be attached to the source output surface already.
   DCHECK(mailbox_.get());
 
   gfx::Size size = output_surface_->SurfaceSize();
-  mirrored_compositor_gl_helper_->CopyTextureFullImage(
-      mirrored_compositor_gl_helper_texture_id_, size);
-  // Insert a barrier to make the copy show up in the mirroring compositor's
-  // mailbox. Since the the compositor contexts and the ImageTransportFactory's
-  // GLHelper are all on the same GPU channel, this is sufficient instead of
-  // plumbing through a sync point.
-  mirrored_compositor_gl_helper_->InsertOrderingBarrier();
 
   // Request full redraw on mirroring compositor.
   for (LayerData* layer_data : mirroring_layers_)
     UpdateTexture(layer_data, size, layer_data->layer->bounds());
+  composition_count_ = mirroring_layers_.size();
 }
 
 void ReflectorImpl::OnSourcePostSubBuffer(const gfx::Rect& rect) {
-  if (mirroring_layers_.empty())
+  if (mirroring_layers_.empty()) {
+    if (!composition_started_callback_.is_null())
+      composition_started_callback_.Run();
     return;
+  }
+
   // Should be attached to the source output surface already.
   DCHECK(mailbox_.get());
 
   gfx::Size size = output_surface_->SurfaceSize();
-  mirrored_compositor_gl_helper_->CopyTextureSubImage(
-      mirrored_compositor_gl_helper_texture_id_, rect);
-  // Insert a barrier to make the copy show up in the mirroring compositor's
-  // mailbox. Since the the compositor contexts and the ImageTransportFactory's
-  // GLHelper are all on the same GPU channel, this is sufficient instead of
-  // plumbing through a sync point.
-  mirrored_compositor_gl_helper_->InsertOrderingBarrier();
 
   int y = rect.y();
   // Flip the coordinates to compositor's one.
@@ -162,6 +166,7 @@ void ReflectorImpl::OnSourcePostSubBuffer(const gfx::Rect& rect) {
   // Request redraw of the dirty portion in mirroring compositor.
   for (LayerData* layer_data : mirroring_layers_)
     UpdateTexture(layer_data, size, mirroring_rect);
+  composition_count_ = mirroring_layers_.size();
 }
 
 static void ReleaseMailbox(scoped_refptr<OwnedMailbox> mailbox,