sync compositor: Signal async frame on IO thread

android_webview/browser/hardware_renderer.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "android_webview/browser/hardware_renderer.h"
 
 #include <utility>
 
 #include "android_webview/browser/aw_gl_surface.h"
 #include "android_webview/browser/aw_render_thread_context_provider.h"
@@ skipping 43 matching lines @@
   ReturnResourcesInChildFrame();
 }
 
 void HardwareRenderer::CommitFrame() {
   TRACE_EVENT0("android_webview", "CommitFrame");
   scroll_offset_ = render_thread_manager_->GetScrollOffsetOnRT();
   std::unique_ptr<ChildFrame> child_frame =
       render_thread_manager_->PassFrameOnRT();
   if (!child_frame.get())
     return;
-
-  last_committed_compositor_frame_sink_id_ =
-      child_frame->compositor_frame_sink_id;
   ReturnResourcesInChildFrame();
+  frame_future_ = render_thread_manager_->PassFrameFutureOnRT();
   child_frame_ = std::move(child_frame);
-  DCHECK(child_frame_->frame.get());
 }
 
 void HardwareRenderer::DrawGL(AwDrawGLInfo* draw_info) {
   TRACE_EVENT0("android_webview", "HardwareRenderer::DrawGL");
 
+  if (frame_future_) {
+    TRACE_EVENT0("android_webview", "GetFrame");
+    DCHECK(child_frame_);
+    DCHECK(!child_frame_->frame);
+
+    std::unique_ptr<content::SynchronousCompositor::Frame> frame =
+        frame_future_->getFrame();
+    if (frame) {
+      child_frame_->compositor_frame_sink_id = frame->compositor_frame_sink_id;
+      child_frame_->frame = std::move(frame->frame);
+    } else {
+      child_frame_.reset();
+    }
+    frame_future_ = nullptr;
+  }
+
+  if (child_frame_) {
+    last_committed_compositor_frame_sink_id_ =
+        child_frame_->compositor_frame_sink_id;
+  }
+
   // We need to watch if the current Android context has changed and enforce
   // a clean-up in the compositor.
   EGLContext current_context = eglGetCurrentContext();
   DCHECK(current_context) << "DrawGL called without EGLContext";
 
   // TODO(boliu): Handle context loss.
   if (last_egl_context_ != current_context)
     DLOG(WARNING) << "EGLContextChanged";
 
   // SurfaceFactory::SubmitCompositorFrame might call glFlush. So calling it
@@ skipping 115 matching lines @@
     const cc::ReturnedResourceArray& resources,
     const CompositorID& compositor_id,
     uint32_t compositor_frame_sink_id) {
   if (compositor_frame_sink_id != last_committed_compositor_frame_sink_id_)
     return;
   render_thread_manager_->InsertReturnedResourcesOnRT(resources, compositor_id,
                                                       compositor_frame_sink_id);
 }
 
 }  // namespace android_webview