Refactoring DevToolsBridgeServer.

components/devtools_bridge/android/java/src/org/chromium/components/devtools_bridge/gcd/MessageWriter.java

Index: components/devtools_bridge/android/java/src/org/chromium/components/devtools_bridge/gcd/MessageWriter.java
diff --git a/components/devtools_bridge/android/java/src/org/chromium/components/devtools_bridge/gcd/MessageWriter.java b/components/devtools_bridge/android/java/src/org/chromium/components/devtools_bridge/gcd/MessageWriter.java
index a95141d71150fc9fb20a48f3329f7926d2a11360..2d7388fb206cf558524ab810a96df28a6946f360 100644
--- a/components/devtools_bridge/android/java/src/org/chromium/components/devtools_bridge/gcd/MessageWriter.java
+++ b/components/devtools_bridge/android/java/src/org/chromium/components/devtools_bridge/gcd/MessageWriter.java
@@ -50,6 +50,19 @@ public final class MessageWriter {
         return this;
     }
 
+    /**
+     * Writes body of devices/<instanceId> PATCH request.
+     */
+    public MessageWriter writeDeviceGCMChannelPatch(String gcmChannelId) throws IOException {
+        mWriter.beginObject();
+        mWriter.name("channel");
+        mWriter.beginObject();
+        mWriter.name("gcmRegistrationId").value(gcmChannelId);
+        mWriter.endObject();
+        mWriter.endObject();
+        return this;
+    }
+
     private void writeDeviceDraft(InstanceDescription description) throws IOException {
         mWriter.beginObject();
         mWriter.name("deviceKind").value("vendor");