cc: Add support for partial swaps when using impl-side painting.

cc/trees/layer_tree_host_impl.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_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 1113 matching lines @@
 
 void LayerTreeHostImpl::EvictTexturesForTesting() {
   EnforceManagedMemoryPolicy(ManagedMemoryPolicy(0));
 }
 
 void LayerTreeHostImpl::BlockNotifyReadyToActivateForTesting(bool block) {
   NOTREACHED();
 }
 
 void LayerTreeHostImpl::DidInitializeVisibleTileForTesting() {
+  // Add arbitrary damage, to trigger prepare-to-draws.
+  // Here, setting damage as viewport size, used only for testing.
+  SetFullRootLayerDamage();
   DidInitializeVisibleTile();
 }
 
 void LayerTreeHostImpl::EnforceManagedMemoryPolicy(
     const ManagedMemoryPolicy& policy) {
 
   bool evicted_resources = client_->ReduceContentsTextureMemoryOnImplThread(
       visible_ ? policy.bytes_limit_when_visible : 0,
       ManagedMemoryPolicy::PriorityCutoffToValue(
           visible_ ? policy.priority_cutoff_when_visible
@@ skipping 55 matching lines @@
 }
 
 void LayerTreeHostImpl::DidModifyTilePriorities() {
   DCHECK(settings_.impl_side_painting);
   // Mark priorities as dirty and schedule a ManageTiles().
   tile_priorities_dirty_ = true;
   client_->SetNeedsManageTilesOnImplThread();
 }
 
 void LayerTreeHostImpl::DidInitializeVisibleTile() {
-  // TODO(reveman): Determine tiles that changed and only damage
-  // what's necessary.
-  SetFullRootLayerDamage();
   if (client_ && !client_->IsInsideDraw())
     client_->DidInitializeVisibleTileOnImplThread();
 }
 
 void LayerTreeHostImpl::NotifyReadyToActivate() {
   client_->NotifyReadyToActivate();
 }
 
+void LayerTreeHostImpl::NotifyTileInitialized(const Tile* tile) {
+  if (!active_tree_)
+    return;
+
+  LayerImpl* layer_impl =
+      active_tree_->FindActiveTreeLayerById(tile->layer_id());
+  if (layer_impl) {
+    gfx::RectF layer_damage_rect =
+        gfx::ScaleRect(tile->content_rect(), 1.f / tile->contents_scale());
+    layer_impl->AddDamageRect(layer_damage_rect);
+  }
+}
+
 void LayerTreeHostImpl::SetMemoryPolicy(const ManagedMemoryPolicy& policy) {
   SetManagedMemoryPolicy(policy, zero_budget_);
 }
 
 void LayerTreeHostImpl::SetTreeActivationCallback(
     const base::Closure& callback) {
   DCHECK(proxy_->IsImplThread());
   DCHECK(settings_.impl_side_painting || callback.is_null());
   tree_activation_callback_ = callback;
 }
@@ skipping 1827 matching lines @@
   swap_promise_monitor_.erase(monitor);
 }
 
 void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
   std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
   for (; it != swap_promise_monitor_.end(); it++)
     (*it)->OnSetNeedsRedrawOnImpl();
 }
 
 }  // namespace cc