Pass the quad's rect (contents_rect) origin to skia image filters as an offset in the CTM.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index d1cbec3dd608ad8022206e35561eb73e2d63e10e..3b5d138fb5c7be7fb93c0e3e1bedc4958b5e74c3 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -515,6 +515,7 @@ static inline SkBitmap ApplyFilters(GLRenderer* renderer,
 }
 
 static SkBitmap ApplyImageFilter(GLRenderer* renderer,
+                                 gfx::Rect rect,

[danakj, 2013/08/19 21:09:08]

better variable name than the type of the variable, what this input represents
to this function?

why pass in a rect but only use the origin? how about passing in just the rect's
OffsetFromOrigin()?

                                  SkImageFilter* filter,
                                  ScopedResource* source_texture_resource) {
   if (!filter)
@@ -581,6 +582,7 @@ static SkBitmap ApplyImageFilter(GLRenderer* renderer,
   SkPaint paint;
   paint.setImageFilter(filter);
   canvas.clear(SK_ColorTRANSPARENT);
+  canvas.translate(SkFloatToScalar(rect.x()), SkFloatToScalar(rect.y()));
   canvas.drawSprite(source, 0, 0, &paint);
 
   // Flush skia context so that all the rendered stuff appears on the
@@ -777,8 +779,8 @@ void GLRenderer::DrawRenderPassQuad(DrawingFrame* frame,
       // in the compositor.
       use_color_matrix = true;
     } else {
-      filter_bitmap =
-          ApplyImageFilter(this, quad->filter.get(), contents_texture);
+      filter_bitmap = ApplyImageFilter(
+          this, quad->rect, quad->filter.get(), contents_texture);
     }
   } else if (!quad->filters.IsEmpty()) {
     FilterOperations optimized_filters =