Fixed crashes in CrNetEnvironment::ConfigureSdchOnNetworkThread()

ios/crnet/CrNet.mm

 // Copyright 2014 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.
 
 #import "ios/crnet/CrNet.h"
 
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/net/crn_http_protocol_handler.h"
 #import "ios/crnet/crnet_environment.h"
@@ skipping 41 matching lines @@
   }
 
   g_chrome_net->Install();
   g_chrome_net->SetHTTPProtocolHandlerRegistered(true);
   g_chrome_net->SetRequestFilterBlock(g_request_filter_block);
 }
 
 + (void)install {
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
+    if (![NSThread isMainThread]) {
+      dispatch_sync(dispatch_get_main_queue(), ^(void) {
+        [self installInternal];
+      });
+    } else {
       [self installInternal];
+    }
   });
 }
 
 + (void)installIntoSessionConfiguration:(NSURLSessionConfiguration*)config {
   g_chrome_net->InstallIntoSessionConfiguration(config);
 }
 
 + (void)installWithPartialUserAgent:(NSString *)partialUserAgent {
   [self setPartialUserAgent:partialUserAgent];
   [self install];
@@ skipping 56 matching lines @@
   }
 }
 
 + (void)clearCacheWithCompletionCallback:(ClearCacheCallback)clearCacheCallback {
   if (g_chrome_net) {
     g_chrome_net->ClearCache(clearCacheCallback);
   }
 }
 
 @end