cc: Move draw params from SetExternalDrawConstraints to OnDraw

cc/test/layer_tree_pixel_test.cc

 // Copyright 2013 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/test/layer_tree_pixel_test.h"
 
 #include "base/command_line.h"
 #include "base/path_service.h"
 #include "cc/base/switches.h"
 #include "cc/layers/solid_color_layer.h"
@@ skipping 56 matching lines @@
     return;
 
   DirectRenderer* renderer = static_cast<DirectRenderer*>(impl->renderer());
   renderer->SetEnlargePassTextureAmountForTesting(enlarge_texture_amount_);
 
   gfx::Rect viewport = impl->DeviceViewport();
   // The viewport has a 0,0 origin without external influence.
   EXPECT_EQ(gfx::Point().ToString(), viewport.origin().ToString());
   // Be that influence!
   viewport += gfx::Vector2d(20, 10);
-  bool resourceless_software_draw = false;
-  gfx::Transform identity = gfx::Transform();
-  impl->SetExternalDrawConstraints(identity,
-                                   viewport,
-                                   viewport,
-                                   viewport,
-                                   identity,
-                                   resourceless_software_draw);
+  impl->SetExternalViewportForTesting(viewport);

[boliu, 2015/12/15 23:46:45]

This one I'm confused. Not sure where this magic translate(20,10) comes from or
why it's needed.

Removing this only breaks two pixel tests:
ImageScaledBackgroundFilter.ImageFilterScaled_GL
LayerTreeHostFiltersPixelTest.BackgroundFilterBlurOffAxis

Resulting image in both tests differs only by 11 pixels. They visually look the
same, so it's not a shift of the whole image or anything. Should I just
rebaseline these and remove this?

[danakj, 2015/12/16 23:57:53]

Hrm, that is very weird. Pretty sure this was meant to move the contents of the
test outputs or something.. well, I think the right thing to test for a pixel
test wrt to this would be to call DrawFrame with a viewport rect of choice
directly with other pixel tests, and not for these layer tree tests, so ok.

   EXPECT_EQ(viewport.ToString(), impl->DeviceViewport().ToString());
 }
 
 scoped_ptr<CopyOutputRequest> LayerTreePixelTest::CreateCopyOutputRequest() {
   return CopyOutputRequest::CreateBitmapRequest(
       base::Bind(&LayerTreePixelTest::ReadbackResult, base::Unretained(this)));
 }
 
 void LayerTreePixelTest::ReadbackResult(scoped_ptr<CopyOutputResult> result) {
   ASSERT_TRUE(result->HasBitmap());
@@ skipping 186 matching lines @@
   return bitmap;
 }
 
 void LayerTreePixelTest::Finish() {
   scoped_ptr<gpu::GLInProcessContext> context = CreateTestInProcessContext();
   GLES2Interface* gl = context->GetImplementation();
   gl->Finish();
 }
 
 }  // namespace cc