Move glue code of blob channel to blimp_client_context_impl.

blimp/client/core/compositor/BUILD.gn

Index: blimp/client/core/compositor/BUILD.gn
diff --git a/blimp/client/core/compositor/BUILD.gn b/blimp/client/core/compositor/BUILD.gn
index 5256a404fbcfd38e217248c0cf9e4aab04efc1de..9c1427d01619d9c7f537be8e9b253410a19bc078 100644
--- a/blimp/client/core/compositor/BUILD.gn
+++ b/blimp/client/core/compositor/BUILD.gn
@@ -19,6 +19,8 @@ source_set("compositor") {
     "blimp_output_surface.h",
     "blob_image_serialization_processor.cc",
     "blob_image_serialization_processor.h",
+    "blob_manager.cc",
+    "blob_manager.h",
     "decoding_image_generator.cc",
     "decoding_image_generator.h",
     "delegated_output_surface.cc",
@@ -55,6 +57,7 @@ source_set("unit_tests") {
     "blimp_client_picture_cache_unittest.cc",
     "blimp_compositor_manager_unittest.cc",
     "blimp_compositor_unittest.cc",
+    "blob_manager_unittest.cc",
     "delegated_output_surface_unittest.cc",
   ]