cc/blimp: Add synchronization for scroll/scale state.

cc/proto/client_state_update.proto

Index: cc/proto/client_state_update.proto
diff --git a/blimp/common/proto/blob_channel.proto b/cc/proto/client_state_update.proto
similarity index 53%
copy from blimp/common/proto/blob_channel.proto
copy to cc/proto/client_state_update.proto
index 0f862f71cb2e426f8f6a2d3f156b1cc94b219201..c1ae4908ff7b71a0f8878f5486081f28b891fcfe 100644
--- a/blimp/common/proto/blob_channel.proto
+++ b/cc/proto/client_state_update.proto
@@ -6,16 +6,16 @@ syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
-package blimp;
+import "vector2df.proto";
 
-message TransferBlob {
-  optional string blob_id = 1;
-  optional bytes payload = 2;
-}
+package cc.proto;
 
-message BlobChannelMessage {
-  oneof type {
-    // Engine => Client types.
-    TransferBlob transfer_blob = 1;
-  }
+message ScrollUpdate {
+  optional int32 layer_id = 1;
+  optional Vector2dF scroll_delta = 2;
 }
+
+message ClientStateUpdate {
+  repeated ScrollUpdate scroll_updates = 1;
+  optional float page_scale_delta = 2;
+}