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 519 matching lines @@
       // Pretend like Javascript updated the scroll position itself with a
       // change of main_thread_scroll.
       root->setScrollOffset(initial_scroll_ + main_thread_scroll_ + impl_thread_scroll1_);
     }
   }
 
   virtual bool canActivatePendingTree() OVERRIDE {
     return can_activate_;
   }
 
+  virtual void commitCompleteOnThread(LayerTreeHostImpl* impl) OVERRIDE {
+    // We force a second draw here of the first commit before activating
+    // the second commit.
+    if (impl->activeTree()->source_frame_number() == 0)
+      impl->setNeedsRedraw();
+  }
+
   virtual void drawLayersOnThread(LayerTreeHostImpl* impl) OVERRIDE {
     ImplSidePaintingScrollTest::drawLayersOnThread(impl);
 
     LayerImpl* root = impl->rootLayer();
     root->setScrollable(true);
     root->setMaxScrollOffset(gfx::Vector2d(100, 100));
 
     LayerImpl* pending_root =
         impl->activeTree()->FindPendingTreeLayerById(root->id());
 
     switch (impl->activeTree()->source_frame_number()) {
       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();
+
+          // commitCompleteOnThread will trigger this function again
+          // and cause us to take the else clause.
         } 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