[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 99e3137de40b19941a20e34fd578eb4709513574..ae1202341672dc73bae7409c189726302ef1ff63 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"
@@ -427,6 +428,14 @@ 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;
+  }
+
   void ReportFixedRasterScaleUseCounters(
       bool has_fixed_raster_scale_blurry_content,
       bool has_fixed_raster_scale_potential_performance_regression);
@@ -452,6 +461,7 @@ 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;
   }
@@ -585,6 +595,8 @@ 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_;