Adding the Copresence RpcHandler and HttpPost helper.

components/copresence/public/copresence_client.h

Index: components/copresence/public/copresence_client.h
diff --git a/components/copresence/public/copresence_client.h b/components/copresence/public/copresence_client.h
index 40b8bf97bfe4720e83416fae7eabd5e89574a568..867276a44cb365bd7ad3ef70d98595a559c177e8 100644
--- a/components/copresence/public/copresence_client.h
+++ b/components/copresence/public/copresence_client.h
@@ -11,7 +11,6 @@
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
 #include "components/copresence/proto/rpcs.pb.h"
 #include "components/copresence/public/copresence_client_delegate.h"
 
@@ -39,7 +38,7 @@ struct PendingRequest {
 // functionality. This class handles all the initialization and delegation of
 // copresence tasks. Any user of copresence only needs to interact with this
 // client.
-class CopresenceClient : public base::SupportsWeakPtr<CopresenceClient> {
+class CopresenceClient {
  public:
   // The delegate must outlive us.
   explicit CopresenceClient(CopresenceClientDelegate* delegate);
@@ -54,9 +53,6 @@ class CopresenceClient : public base::SupportsWeakPtr<CopresenceClient> {
                             const std::string& app_id,
                             const StatusCallback& callback);
 
-  // Called before the API (and thus the Client) is destructed.
-  void Shutdown();
-
  private:
   void CompleteInitialization();
   void InitStepComplete(const std::string& step, bool success);