Added FrameFuture class

content/public/browser/android/synchronous_compositor.cc

Index: content/public/browser/android/synchronous_compositor.cc
diff --git a/content/public/browser/android/synchronous_compositor.cc b/content/public/browser/android/synchronous_compositor.cc
index 616530fc7de376d22f2008ab69c58e33307bbb10..fbdc5b23e1cc4b4a7199c6872d3464e02560b3bb 100644
--- a/content/public/browser/android/synchronous_compositor.cc
+++ b/content/public/browser/android/synchronous_compositor.cc
@@ -18,6 +18,28 @@ SynchronousCompositor::Frame::Frame(Frame&& rhs)
     : compositor_frame_sink_id(rhs.compositor_frame_sink_id),
       frame(std::move(rhs.frame)) {}
 
+SynchronousCompositor::FrameFuture::FrameFuture()
+    : waitable_event_(base::WaitableEvent::ResetPolicy::MANUAL,
+                      base::WaitableEvent::InitialState::NOT_SIGNALED) {}
+
+SynchronousCompositor::FrameFuture::~FrameFuture() {}
+
+void SynchronousCompositor::FrameFuture::setFrame(
+    std::unique_ptr<Frame> frame) {
+  frame_ = std::move(frame);
+  waitable_event_.Signal();
+}
+
+std::unique_ptr<SynchronousCompositor::Frame>
+SynchronousCompositor::FrameFuture::getFrame() {
+#if DCHECK_IS_ON()
+  DCHECK(!waited_);
+  waited_ = true;
+#endif
+  waitable_event_.Wait();
+  return std::move(frame_);
+}
+
 SynchronousCompositor::Frame& SynchronousCompositor::Frame::operator=(
     Frame&& rhs) {
   compositor_frame_sink_id = rhs.compositor_frame_sink_id;