VideoLayerImpl: subtract 1 from visible size when calculating tex stretch.

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 39b8ef20c59f072bcbc8f6815aa9d66ea8a82edb..923767e526348c35363039edf2c83f2bc97d734d 100644
--- a/cc/layers/video_layer_impl.cc
+++ b/cc/layers/video_layer_impl.cc
@@ -184,11 +184,17 @@ void VideoLayerImpl::AppendQuads(RenderPass* render_pass,
   if (visible_quad_rect.IsEmpty())
     return;
 
-  // Pixels for macroblocked formats.
+  // Pixels for macroblocked formats. To prevent sampling outside the visible
+  // rect, stretch the video if needed.
+  gfx::Rect visible_sample_rect = frame_->visible_rect();
+  if (visible_rect.width() < coded_size.width() && visible_rect.width() > 1)
+    visible_sample_rect.set_width(visible_rect.width() - 1);
+  if (visible_rect.height() < coded_size.height() && visible_rect.height() > 1)
+    visible_sample_rect.set_height(visible_rect.height() - 1);
   const float tex_width_scale =
-      static_cast<float>(visible_rect.width()) / coded_size.width();
+      static_cast<float>(visible_sample_rect.width()) / coded_size.width();
   const float tex_height_scale =
-      static_cast<float>(visible_rect.height()) / coded_size.height();
+      static_cast<float>(visible_sample_rect.height()) / coded_size.height();
 
   switch (frame_resource_type_) {
     // TODO(danakj): Remove this, hide it in the hardware path.
@@ -257,12 +263,12 @@ void VideoLayerImpl::AppendQuads(RenderPass* render_pass,
           static_cast<float>(ya_tex_size.width()) / uv_tex_size.width();
       float uv_subsampling_factor_y =
           static_cast<float>(ya_tex_size.height()) / uv_tex_size.height();
-      gfx::RectF ya_tex_coord_rect(visible_rect);
+      gfx::RectF ya_tex_coord_rect(visible_sample_rect);
       gfx::RectF uv_tex_coord_rect(
-          visible_rect.x() / uv_subsampling_factor_x,
-          visible_rect.y() / uv_subsampling_factor_y,
-          visible_rect.width() / uv_subsampling_factor_x,
-          visible_rect.height() / uv_subsampling_factor_y);
+          visible_sample_rect.x() / uv_subsampling_factor_x,
+          visible_sample_rect.y() / uv_subsampling_factor_y,
+          visible_sample_rect.width() / uv_subsampling_factor_x,
+          visible_sample_rect.height() / uv_subsampling_factor_y);
 
       YUVVideoDrawQuad* yuv_video_quad =
           render_pass->CreateAndAppendDrawQuad<YUVVideoDrawQuad>();