[blimp] Add SkPicture caching support.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 24a5ba4e4ab91cd60d40b57b6daac3aa635afd0e..b58ca26132ecfe6a58a82d7efebb90802bfbf439 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -34,6 +34,7 @@
 #include "cc/output/output_surface.h"
 #include "cc/output/renderer_capabilities.h"
 #include "cc/output/swap_promise.h"
+#include "cc/proto/picture_cache.h"
 #include "cc/resources/resource_format.h"
 #include "cc/resources/scoped_ui_resource.h"
 #include "cc/surfaces/surface_sequence.h"
@@ -421,6 +422,14 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
     return image_serialization_processor_;
   }
 
+  EnginePictureCache* engine_picture_cache() const {
+    return engine_picture_cache_ ? engine_picture_cache_.get() : nullptr;
+  }
+
+  ClientPictureCache* client_picture_cache() const {
+    return client_picture_cache_ ? client_picture_cache_.get() : nullptr;
+  }
+
  protected:
   LayerTreeHost(InitParams* params, CompositorMode mode);
   void InitializeThreaded(
@@ -442,6 +451,7 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
       std::unique_ptr<TaskRunnerProvider> task_runner_provider,
       std::unique_ptr<Proxy> proxy_for_testing,
       std::unique_ptr<BeginFrameSource> external_begin_frame_source);
+  void InitializePictureCacheForTesting();
   void SetOutputSurfaceLostForTesting(bool is_lost) {
     output_surface_lost_ = is_lost;
   }
@@ -575,6 +585,8 @@ class CC_EXPORT LayerTreeHost : public MutatorHostClient {
   TaskGraphRunner* task_graph_runner_;
 
   ImageSerializationProcessor* image_serialization_processor_;
+  std::unique_ptr<EnginePictureCache> engine_picture_cache_;
+  std::unique_ptr<ClientPictureCache> client_picture_cache_;
 
   std::vector<std::unique_ptr<SwapPromise>> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;