Update GatherPixelRefDevice to the new SkImage/SkPixelRef API

cc/playback/display_list_recording_source_unittest.cc

 // Copyright 2015 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 <vector>
 
 #include "cc/base/region.h"
 #include "cc/playback/display_list_raster_source.h"
 #include "cc/test/fake_content_layer_client.h"
 #include "cc/test/fake_display_list_recording_source.h"
@@ skipping 11 matching lines @@
 TEST_F(DisplayListRecordingSourceTest, DiscardablePixelRefsWithTransform) {
   gfx::Size grid_cell_size(128, 128);
   gfx::Rect recorded_viewport(256, 256);
 
   scoped_ptr<FakeDisplayListRecordingSource> recording_source =
       FakeDisplayListRecordingSource::CreateFilledRecordingSource(
           recorded_viewport.size());
   recording_source->SetGridCellSize(grid_cell_size);
   SkBitmap discardable_bitmap[2][2];
   gfx::Transform identity_transform;
-  CreateBitmap(gfx::Size(32, 32), "discardable", &discardable_bitmap[0][0]);
+  CreateDiscardableBitmap(gfx::Size(32, 32), &discardable_bitmap[0][0]);
   // Translate transform is equivalent to moving using point.
   gfx::Transform translate_transform;
   translate_transform.Translate(0, 130);
-  CreateBitmap(gfx::Size(32, 32), "discardable", &discardable_bitmap[1][0]);
+  CreateDiscardableBitmap(gfx::Size(32, 32), &discardable_bitmap[1][0]);
   // This moves the bitmap to center of viewport and rotate, this would make
   // this bitmap in all four tile grids.
   gfx::Transform rotate_transform;
   rotate_transform.Translate(112, 112);
   rotate_transform.Rotate(45);
-  CreateBitmap(gfx::Size(32, 32), "discardable", &discardable_bitmap[1][1]);
+  CreateDiscardableBitmap(gfx::Size(32, 32), &discardable_bitmap[1][1]);
 
   gfx::RectF rect(0, 0, 32, 32);
   gfx::RectF translate_rect = rect;
   translate_transform.TransformRect(&translate_rect);
   gfx::RectF rotate_rect = rect;
   rotate_transform.TransformRect(&rotate_rect);
 
   recording_source->add_draw_bitmap_with_transform(discardable_bitmap[0][0],
                                                    identity_transform);
   recording_source->add_draw_bitmap_with_transform(discardable_bitmap[1][0],
@@ skipping 295 matching lines @@
   // layer's bottom edge.
   visible_rect.Offset(0, 231);
   recording_source.UpdateAndExpandInvalidation(
       &client, &invalidation, layer_size, visible_rect, 0,
       RecordingSource::RECORD_NORMALLY);
   EXPECT_EQ(gfx::Rect(0, 0, 8256, 9000), recording_source.recorded_viewport());
 }
 
 }  // namespace
 }  // namespace cc