Make zoom filter independent of the layer size.

cc/render_surface_filters.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/render_surface_filters.h"
 
 #include "base/logging.h"
 #include "skia/ext/refptr.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebFilterOperation.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebFilterOperations.h"
@@ skipping 406 matching lines @@
         paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);
         canvas->saveLayer(NULL, &paint);
         canvas->drawBitmap(state.Source(),
                            op.dropShadowOffset().x,
                            -op.dropShadowOffset().y);
         canvas->restore();
         canvas->drawBitmap(state.Source(), 0, 0);
         break;
       }
       case WebKit::WebFilterOperation::FilterTypeZoom: {
+#ifdef NEW_ZOOM_FILTER // TODO(danakj): Remove this when WebKit rolls.
         SkPaint paint;
+        int width = state.Source().width();
+        int height = state.Source().height();
         skia::RefPtr<SkImageFilter> zoom_filter = skia::AdoptRef(
             new SkMagnifierImageFilter(
-                SkRect::MakeXYWH(op.zoomRect().x,
-                                 op.zoomRect().y,
-                                 op.zoomRect().width,
-                                 op.zoomRect().height),
-                op.amount()));
+                SkRect::MakeXYWH(
+                    (width - (width / op.amount())) / 2.f,
+                    (height - (height / op.amount())) / 2.f,
+                    width / op.amount(),
+                    height / op.amount()),
+                op.zoomInset()));
         paint.setImageFilter(zoom_filter.get());
         canvas->saveLayer(NULL, &paint);
         canvas->drawBitmap(state.Source(), 0, 0);
         canvas->restore();
+#endif
         break;
       }
       case WebKit::WebFilterOperation::FilterTypeBrightness:
       case WebKit::WebFilterOperation::FilterTypeSaturatingBrightness:
       case WebKit::WebFilterOperation::FilterTypeContrast:
       case WebKit::WebFilterOperation::FilterTypeGrayscale:
       case WebKit::WebFilterOperation::FilterTypeSepia:
       case WebKit::WebFilterOperation::FilterTypeSaturate:
       case WebKit::WebFilterOperation::FilterTypeHueRotate:
       case WebKit::WebFilterOperation::FilterTypeInvert:
       case WebKit::WebFilterOperation::FilterTypeOpacity:
         NOTREACHED();
         break;
     }
     state.Swap();
   }
   return state.Source();
 }
 
 }  // namespace cc