Expose locks for CopyFromCompositingSurface/CopyFromBackingStore API

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index dba444dff70b19c755109494fa7471bcc80f3263..12da8878043ea8e31dc051a1fc4f5d6b20a6e664 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -147,7 +147,8 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
       using_delegated_renderer_(CommandLine::ForCurrentProcess()->HasSwitch(
                                     switches::kEnableDelegatedRenderer) &&
                                 !CommandLine::ForCurrentProcess()->HasSwitch(
-                                    switches::kDisableDelegatedRenderer)) {
+                                    switches::kDisableDelegatedRenderer)),
+      locks_on_frame_count_(0) {
   if (!using_delegated_renderer_) {
     texture_layer_ = cc::TextureLayer::Create(NULL);
     layer_ = texture_layer_;
@@ -285,6 +286,9 @@ bool RenderWidgetHostViewAndroid::HasValidFrame() const {
   if (texture_size_in_layer_.IsEmpty())
     return false;
 
+  if (!frame_evictor_->HasFrame())
+    return false;
+
   if (using_delegated_renderer_) {
     if (!delegated_renderer_layer_.get())
       return false;
@@ -375,16 +379,31 @@ bool RenderWidgetHostViewAndroid::IsShowing() {
   return is_showing_ && content_view_core_;
 }
 
-void RenderWidgetHostViewAndroid::LockResources() {
+void RenderWidgetHostViewAndroid::LockSurfaceForCopy() {
   DCHECK(HasValidFrame());
   DCHECK(host_);
-  DCHECK(!host_->is_hidden());
+  DCHECK(frame_evictor_->HasFrame());
   frame_evictor_->LockFrame();
+  locks_on_frame_count_++;
 }
 
-void RenderWidgetHostViewAndroid::UnlockResources() {
+void RenderWidgetHostViewAndroid::UnlockSurfaceForCopy() {
+  if (!frame_evictor_->HasFrame() || locks_on_frame_count_ == 0)
+    return;
+
   DCHECK(HasValidFrame());
   frame_evictor_->UnlockFrame();
+  locks_on_frame_count_--;
+}
+
+void RenderWidgetHostViewAndroid::ReleaseLocksOnSurface() {
+  if (!frame_evictor_->HasFrame()) {
+    DCHECK_EQ(locks_on_frame_count_, 0u);
+    return;
+  }
+  while (locks_on_frame_count_ > 0) {
+    UnlockSurfaceForCopy();
+  }
 }
 
 gfx::Rect RenderWidgetHostViewAndroid::GetViewBounds() const {
@@ -808,6 +827,18 @@ void RenderWidgetHostViewAndroid::OnSwapCompositorFrame(
     DCHECK(frame->delegated_frame_data);
     DCHECK(!frame->delegated_frame_data->render_pass_list.empty());
 
+    if (locks_on_frame_count_ > 0) {
+      DCHECK(HasValidFrame());
+      base::Closure ack_callback =
+          base::Bind(&RenderWidgetHostViewAndroid::SendDelegatedFrameAck,
+                     weak_ptr_factory_.GetWeakPtr(),
+                     output_surface_id);
+      if (host_->is_hidden())
+        ack_callback.Run();
+      else
+        ack_callbacks_.push(ack_callback);
+      return;

[piman, 2014/03/05 20:14:36]

So, if my understanding is correct, while there is a lock, we discard incoming
frames from the renderer? Should we keep the last one around to  swap in when
the lock count drops to 0?

[powei, 2014/03/06 07:41:40]

Yes
Done.  PTAL.

+    }
     cc::RenderPass* root_pass =
         frame->delegated_frame_data->render_pass_list.back();
     texture_size_in_layer_ = root_pass->output_rect.size();
@@ -1260,6 +1291,9 @@ void RenderWidgetHostViewAndroid::SetContentViewCore(
   if (content_view_core_ && !using_synchronous_compositor_)
     content_view_core_->GetWindowAndroid()->RemoveObserver(this);
 
+  if (content_view_core != content_view_core_)
+    ReleaseLocksOnSurface();
+
   content_view_core_ = content_view_core;
 
   if (GetBrowserAccessibilityManager()) {
@@ -1293,6 +1327,7 @@ void RenderWidgetHostViewAndroid::OnDetachCompositor() {
 }
 
 void RenderWidgetHostViewAndroid::OnLostResources() {
+  ReleaseLocksOnSurface();
   if (texture_layer_.get())
     texture_layer_->SetIsDrawable(false);
   if (delegated_renderer_layer_.get())