Add hints for potential overlay promotion on android.

components/display_compositor/compositor_overlay_candidate_validator_android.cc

Index: components/display_compositor/compositor_overlay_candidate_validator_android.cc
diff --git a/components/display_compositor/compositor_overlay_candidate_validator_android.cc b/components/display_compositor/compositor_overlay_candidate_validator_android.cc
index 805dae3b917d7147b70e749309e068ab3518483e..b4edfd7126e78bfec80a7af0bf882275d2f237f0 100644
--- a/components/display_compositor/compositor_overlay_candidate_validator_android.cc
+++ b/components/display_compositor/compositor_overlay_candidate_validator_android.cc
@@ -34,6 +34,25 @@ void CompositorOverlayCandidateValidatorAndroid::CheckOverlaySupport(
 
   if (!candidates->empty()) {
     cc::OverlayCandidate& candidate = candidates->front();
+
+    if (candidate.is_backed_by_surface_texture) {
+      // This quad would be promoted if it were backed by a SurfaceView.  Since
+      // it isn't, we can't promote it.  We do want to mark it as promotable,
+      // since the whole point of signalling this is to help whoever creates
+      // the resource to decide whether a SurfaceTexture or SurfaceView is more
+      // appropriate to use.
+      promotable_resources_.insert(candidate.resource_id);
+      return;
+    }
+
+    // This quad will be promoted.  We clear the promotable set here, since we
+    // can only promote a single quad.  Otherwise, somebody might try to back
+    // one of the promotable quads with a SurfaceView, and either it or |quad|
+    // would have to fall back to a texture.
+    // We could re-insert |candidate.resource_id| back into the set, but the
+    // quad that refers to it won't be in the list anyway after promotion.
+    promotable_resources_.clear();
+
     candidate.display_rect =
         gfx::RectF(gfx::ToEnclosingRect(candidate.display_rect));
     candidate.overlay_handled = true;
@@ -50,4 +69,13 @@ bool CompositorOverlayCandidateValidatorAndroid::AllowCALayerOverlays() {
 void CompositorOverlayCandidateValidatorAndroid::SetSoftwareMirrorMode(
     bool enabled) {}
 
+void CompositorOverlayCandidateValidatorAndroid::ClearPromotableResources() {
+  promotable_resources_.clear();
+}
+
+bool CompositorOverlayCandidateValidatorAndroid::IsResourcePromotable(
+    cc::ResourceId resource_id) {
+  return promotable_resources_.count(resource_id) > 0;
+}
+
 }  // namespace display_compositor