Enable sampling from DXGI NV12 formats in GLRenderer.

cc/layers/video_layer_impl.cc

Index: cc/layers/video_layer_impl.cc
diff --git a/cc/layers/video_layer_impl.cc b/cc/layers/video_layer_impl.cc
index 56eb67764a72f77331575ca1616c1316523e9480..e01d566086e386988530152301b48f95915a4732 100644
--- a/cc/layers/video_layer_impl.cc
+++ b/cc/layers/video_layer_impl.cc
@@ -233,8 +233,6 @@ void VideoLayerImpl::AppendQuads(RenderPass* render_pass,
       break;
     }
     case VideoFrameExternalResources::YUV_RESOURCE: {
-      DCHECK_GE(frame_resources_.size(), 3u);
-
       YUVVideoDrawQuad::ColorSpace color_space = YUVVideoDrawQuad::REC_601;
       int videoframe_color_space;
       if (frame_->metadata()->GetInteger(media::VideoFrameMetadata::COLOR_SPACE,
@@ -251,12 +249,18 @@ void VideoLayerImpl::AppendQuads(RenderPass* render_pass,
           frame_->format(), media::VideoFrame::kUPlane, coded_size);
 
       if (frame_->HasTextures()) {
-        DCHECK_EQ(media::PIXEL_FORMAT_I420, frame_->format());
-        DCHECK_EQ(3u, frame_resources_.size());  // Alpha is not supported yet.
+        if (frame_->format() == media::PIXEL_FORMAT_NV12) {
+          DCHECK_EQ(2u, frame_resources_.size());
+        } else {
+          DCHECK_EQ(media::PIXEL_FORMAT_I420, frame_->format());
+          DCHECK_EQ(3u,
+                    frame_resources_.size());  // Alpha is not supported yet.
+        }
       } else {
         DCHECK(uv_tex_size ==
                media::VideoFrame::PlaneSize(
                    frame_->format(), media::VideoFrame::kVPlane, coded_size));
+        DCHECK_GE(frame_resources_.size(), 3u);
         DCHECK(frame_resources_.size() <= 3 ||
                ya_tex_size == media::VideoFrame::PlaneSize(
                                   frame_->format(), media::VideoFrame::kAPlane,
@@ -282,7 +286,8 @@ void VideoLayerImpl::AppendQuads(RenderPass* render_pass,
           shared_quad_state, quad_rect, opaque_rect, visible_quad_rect,
           ya_tex_coord_rect, uv_tex_coord_rect, ya_tex_size, uv_tex_size,
           frame_resources_[0].id, frame_resources_[1].id,
-          frame_resources_[2].id,
+          frame_resources_.size() > 2 ? frame_resources_[2].id
+                                      : frame_resources_[1].id,
           frame_resources_.size() > 3 ? frame_resources_[3].id : 0, color_space,
           frame_resource_offset_, frame_resource_multiplier_);
       ValidateQuadResources(yuv_video_quad);