cc: Allow the main thread to cancel commits

cc/trees/layer_tree_host_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/synchronization/lock.h"
@@ skipping 1794 matching lines @@
   virtual void BeginTest() OVERRIDE {
     layer_tree_host()->SetViewportSize(gfx::Size(10, 10));
     layer_tree_host()->root_layer()->SetBounds(gfx::Size(10, 10));
 
     PostSetNeedsCommitToMainThread();
   }
 
   virtual void DidCommit() OVERRIDE {
     if (num_draw_layers_ == 2)
       return;
-    layer_tree_host()->root_layer()->SetNeedsDisplay();
+    layer_tree_host()->SetNeedsCommit();
   }
 
   virtual void CommitCompleteOnThread(LayerTreeHostImpl* impl) OVERRIDE {
     if (num_draw_layers_ == 1)
       num_commit_complete_++;
   }
 
   virtual void DrawLayersOnThread(LayerTreeHostImpl* impl) OVERRIDE {
     num_draw_layers_++;
     if (num_draw_layers_ == 2)
@@ skipping 1195 matching lines @@
 class LayerTreeHostTestDeferredInitialize : public LayerTreeHostTest {
  public:
   virtual void InitializeSettings(LayerTreeSettings* settings) OVERRIDE {
     // PictureLayer can only be used with impl side painting enabled.
     settings->impl_side_painting = true;
     settings->solid_color_scrollbars = true;
   }
 
   virtual void SetupTree() OVERRIDE {
     layer_ = FakePictureLayer::Create(&client_);
+    // Force commits to not be aborted so new frames get drawn, otherwise
+    // the renderer gets deferred initialized but nothing new needs drawing.
+    layer_->set_always_update_resources(true);

[danakj, 2013/07/23 15:35:27]

Is this saying that when we switch to GL mode, the TileManager isn't creating GL
resources which would cause us to draw again? I thought it was and that was why
we were flakily getting 2 draws in this test.

Either way if we're supposed to draw, we need to produce a frame a different
type of frame. Sounds like switching modes needs to cause a full root layer
damage?

[enne (OOO), 2013/07/23 16:58:21]

I am not convinced of that.  If you switch modes but there's been no damage,
then the current frame is still good enough and you shouldn't need to draw
again.

[danakj, 2013/07/23 17:00:11]

I guess it depends what it means to switch modes, like if the embedder switched
to software mode then it would want a software frame, etc.

But.. then it could be the one responsible for causing that damage, it wouldn't
need to be implicit.

OK This LGTM as is, thanks!

[boliu, 2013/07/23 17:19:44]

Right. The reason there's a SetNeedsCommit is mailbox resources could be dropped
and needs to be committed again to the impl side. It is not for triggering draws
(although this test did depend on that behavior)

     layer_tree_host()->SetRootLayer(layer_);
     LayerTreeHostTest::SetupTree();
   }
 
   virtual void BeginTest() OVERRIDE {
     did_initialize_gl_ = false;
     did_release_gl_ = false;
     PostSetNeedsCommitToMainThread();
   }
 
@@ skipping 263 matching lines @@
         // Layers added to the tree get committed.
         ++expected_push_properties_child_;
         ++expected_push_properties_grandchild_;
         break;
       case 15:
         grandchild_->SetPosition(gfx::Point(1, 1));
         // The modified layer needs commit
         ++expected_push_properties_grandchild_;
         break;
       case 16:
+        // SetNeedsDisplay does not always set needs commit (so call it
+        // explicitly), but is a property change.
         child_->SetNeedsDisplay();
-        // The modified layer needs commit
         ++expected_push_properties_child_;
+        layer_tree_host()->SetNeedsCommit();
         break;
       case 17:
         EndTest();
         break;
     }
 
     // Content/Picture layers require PushProperties every commit that they are
     // in the tree.
     if ((leaf_content_layer_.get() && leaf_content_layer_->layer_tree_host()) ||
         (leaf_picture_layer_.get() && leaf_picture_layer_->layer_tree_host()))
@@ skipping 554 matching lines @@
 TEST_F(LayerTreeHostTestTreeActivationCallback, DirectRenderer) {
   RunTest(true, false, true);
 }
 
 TEST_F(LayerTreeHostTestTreeActivationCallback, DelegatingRenderer) {
   RunTest(true, true, true);
 }
 
 }  // namespace
 }  // namespace cc