Convert ChromeViewMsg_SetFieldTrialGroup to use mojo.

chrome/common/render_messages.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Multiply-included file, no traditional include guard.
 #include <stdint.h>
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
@@ skipping 106 matching lines @@
 // which is late enough to not be thrown out, and early enough to be before
 // onload events are fired.
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_WebUIJavaScript,
                     base::string16  /* javascript */)
 #endif
 
 // Tells the render frame to load all blocked plugins with the given identifier.
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_LoadBlockedPlugins,
                     std::string /* identifier */)
 
-// Tells the renderer to create a FieldTrial, and by using a 100% probability
-// for the FieldTrial, forces the FieldTrial to have assigned group name.
-IPC_MESSAGE_CONTROL2(ChromeViewMsg_SetFieldTrialGroup,
-                     std::string /* field trial name */,
-                     std::string /* group name that was assigned. */)
-
 // Sent to allow or forbid the running of insecure mixed-content.
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetAllowRunningInsecureContent,
                     bool /* allowed */)
 
 IPC_MESSAGE_ROUTED0(ChromeViewMsg_ReloadFrame)
 
 // Tells the renderer whether or not a file system access has been allowed.
 IPC_MESSAGE_ROUTED2(ChromeViewMsg_RequestFileSystemAccessAsyncResponse,
                     int  /* request_id */,
                     bool /* allowed */)
@@ skipping 252 matching lines @@
 // process so that they can be assigned to an Instant renderer.
 IPC_MESSAGE_CONTROL2(ChromeViewMsg_SetSearchURLs,
                      std::vector<GURL> /* search_urls */,
                      GURL /* new_tab_page_url */)
 
 #if BUILDFLAG(ENABLE_PLUGINS)
 // Sent by the renderer to check if crash reporting is enabled.
 IPC_SYNC_MESSAGE_CONTROL0_1(ChromeViewHostMsg_IsCrashReportingEnabled,
                             bool /* enabled */)
 #endif