cc: Do not request redraw on commit when impl-side painting

cc/layer_tree_host_unittest_scroll.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/layer_tree_host.h"
 
 #include "cc/content_layer.h"
 #include "cc/layer.h"
 #include "cc/layer_impl.h"
 #include "cc/layer_tree_impl.h"
@@ skipping 540 matching lines @@
       case 0:
         if (!impl->pendingTree()) {
           can_activate_ = false;
           EXPECT_VECTOR_EQ(root->scrollDelta(), gfx::Vector2d());
           root->scrollBy(impl_thread_scroll1_);
 
           EXPECT_VECTOR_EQ(root->scrollOffset(), initial_scroll_);
           EXPECT_VECTOR_EQ(root->scrollDelta(), impl_thread_scroll1_);
           EXPECT_VECTOR_EQ(root->sentScrollDelta(), gfx::Vector2d());
           postSetNeedsCommitToMainThread();
+          impl->setNeedsRedraw();

[nduca, 2013/01/15 01:54:54]

any idea why this one happened?

[enne (OOO), 2013/01/15 01:58:35]

Yeah, I talked with Brian about this.  Previously this test assumed there'd be a
redraw post commit that would get kicked off to try to draw the old main frame
again while there was a pending tree.

That said, I wonder if this is a race between the commit and the redraw, where
it could try to redraw and rather than getting into the else block it re-does
the first part of this if block.

I wonder if something like commitComplete should instead set the redraw in this
test.

[brianderson, 2013/01/15 02:01:56]

Will have commit complete trigger setNeedsRedraw once.

         } else {
           can_activate_ = true;
           ASSERT_TRUE(pending_root);
           EXPECT_EQ(impl->pendingTree()->source_frame_number(), 1);
 
           root->scrollBy(impl_thread_scroll2_);
           EXPECT_VECTOR_EQ(root->scrollOffset(), initial_scroll_);
           EXPECT_VECTOR_EQ(root->scrollDelta(),
               impl_thread_scroll1_ + impl_thread_scroll2_);
           EXPECT_VECTOR_EQ(root->sentScrollDelta(), impl_thread_scroll1_);
@@ skipping 32 matching lines @@
   gfx::Vector2d impl_thread_scroll1_;
   gfx::Vector2d impl_thread_scroll2_;
   int num_scrolls_;
   bool can_activate_;
 };
 
 MULTI_THREAD_TEST_F(ImplSidePaintingScrollTestSimple);
 
 }  // namespace
 }  // namespace cc