Export all CWV* symbols from the ios/web_view dynamic library.

ios/web_view/shell/BUILD.gn

 # Copyright 2016 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("//build/config/ios/rules.gni")
 
 ios_app_bundle("ios_web_view_shell") {
   info_plist = "Info.plist"
 
   deps = [
@@ skipping 12 matching lines @@
     "shell_app_delegate.m",
     "shell_delegate.h",
     "shell_delegate.m",
     "shell_exe_main.m",
     "shell_view_controller.h",
     "shell_view_controller.m",
     "translate_controller.h",
     "translate_controller.m",
   ]
 
+  # A workaround for an issue that we need to use the form:
+  #   #include "ios/web_view/public/cwv_export.h"
+  # instead of:
+  #   #include <ChromeWebView/cwv_export.h>
+  # when building this app.
+  #
+  # TODO(crbug.com/704946): Solve the issue and remove this workaround.
+  defines = [ "CWV_IMPLEMENTATION" ]
+
   deps = [
     ":resources",
     "//ios/web_view",
   ]
 
   libs = [
     "CFNetwork.framework",
     "CoreFoundation.framework",
     "CoreGraphics.framework",
     "CoreText.framework",
@@ skipping 16 matching lines @@
     "Default-568h@2x.png",
     "textfield_background@2x.png",
     "toolbar_back@2x.png",
     "toolbar_forward@2x.png",
     "toolbar_stop@2x.png",
   ]
   outputs = [
     "{{bundle_resources_dir}}/{{source_file_part}}",
   ]
 }