Adding test to check for c++ in framework headers.

Bug: webrtc:8469
Change-Id: I336a2aa75638920901c2bddf07fb03cb00ccb83e
Reviewed-on: https://webrtc-review.googlesource.com/38020
Commit-Queue: Peter Hanspers <peterhanspers@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21536}

sdk/BUILD.gn

@@ -542,6 +542,7 @@ if (is_ios || is_mac) {
           ]
 
           sources = [
+            "objc/Framework/UnitTests/RTCDoNotPutCPlusPlusInFrameworkHeaders_xctest.m",
             "objc/Framework/UnitTests/RTCFileVideoCapturer_xctest.mm",
           ]
 

sdk/objc/Framework/UnitTests/RTCDoNotPutCPlusPlusInFrameworkHeaders_xctest.m

@@ -0,0 +1,30 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import <XCTest/XCTest.h>
+
+#import <Foundation/Foundation.h>
+
+#import <WebRTC/WebRTC.h>
+
+@interface RTCDoNotPutCPlusPlusInFrameworkHeaders : XCTestCase
+@end
+
+@implementation RTCDoNotPutCPlusPlusInFrameworkHeaders
+
+- (void)testNoCPlusPlusInFrameworkHeaders {
+  NSString *fullPath = [NSString stringWithFormat:@"%s", __FILE__];
+  NSString *extension = fullPath.pathExtension;
+
+  XCTAssertEqualObjects(
+      @"m", extension, @"Do not rename %@. It should end with .m.", fullPath.lastPathComponent);
+}
+
+@end