OnDrawHardware() implementation with async messages

android_webview/browser/browser_view_renderer.cc

Index: android_webview/browser/browser_view_renderer.cc
diff --git a/android_webview/browser/browser_view_renderer.cc b/android_webview/browser/browser_view_renderer.cc
index e091edc93f872a6291b6314d0e4a87b566292c7a..13c03636c7050bccda417e21dc52ff77c6ebd207 100644
--- a/android_webview/browser/browser_view_renderer.cc
+++ b/android_webview/browser/browser_view_renderer.cc
@@ -239,6 +239,7 @@ bool BrowserViewRenderer::OnDrawHardware() {
     viewport_rect_for_tile_priority = last_on_draw_global_visible_rect_;
   }
 
+  /* Nullptr will be received as this is now async */
   content::SynchronousCompositor::Frame frame =
       compositor_->DemandDrawHw(surface_size,
                                 gfx::Transform(),
@@ -263,6 +264,31 @@ bool BrowserViewRenderer::OnDrawHardware() {
   return true;
 }
 
+void BrowserViewRenderer::OnDrawHardwareProcessFrame(
+    content::SynchronousCompositor::Frame frame) {
+  gfx::Transform transform_for_tile_priority =
+      external_draw_constraints_.transform;
+
+  // If the WebView is on a layer, WebView does not know what transform is
+  // applied onto the layer so global visible rect does not make sense here.
+  // In this case, just use the surface rect for tiling.
+  gfx::Rect viewport_rect_for_tile_priority;
+
+  // Leave viewport_rect_for_tile_priority empty if offscreen_pre_raster_ is on.
+  if (!offscreen_pre_raster_ && !external_draw_constraints_.is_layer) {
+    viewport_rect_for_tile_priority = last_on_draw_global_visible_rect_;
+  }
+
+  std::unique_ptr<ChildFrame> child_frame = base::WrapUnique(new ChildFrame(
+      frame.output_surface_id, std::move(frame.frame), compositor_id_,
+      viewport_rect_for_tile_priority.IsEmpty(), transform_for_tile_priority,
+      offscreen_pre_raster_, external_draw_constraints_.is_layer));
+
+  ReturnUnusedResource(
+      current_compositor_frame_consumer_->PassUncommittedFrameOnUI());
+  current_compositor_frame_consumer_->SetFrameOnUI(std::move(child_frame));
+}
+
 void BrowserViewRenderer::OnParentDrawConstraintsUpdated(
     CompositorFrameConsumer* compositor_frame_consumer) {
   DCHECK(compositor_frame_consumer);