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

ios/web_view/internal/BUILD.gn

Index: ios/web_view/internal/BUILD.gn
diff --git a/ios/web_view/internal/BUILD.gn b/ios/web_view/internal/BUILD.gn
index 444aedad5d739b9c8db3248843b99e6a402ff6b1..3cf407933c3609de5117b91b8172305b1fd4d2fc 100644
--- a/ios/web_view/internal/BUILD.gn
+++ b/ios/web_view/internal/BUILD.gn
@@ -36,6 +36,9 @@ source_set("internal") {
     "web_view_web_state_policy_decider.h",
     "web_view_web_state_policy_decider.mm",
   ]
+
+  defines = [ "CWV_IMPLEMENTATION" ]

[michaeldo, 2017/03/22 23:16:22]

Can you explain what this is for, probably should add explanation to the CL
description to for later reference in case someone has the same question.

[Hiroshi Ichikawa, 2017/03/23 05:03:02]

Added a description to the CL. Also added a short description here as a comment.

[michaeldo, 2017/03/23 15:12:41]

Understand now, thank you!

+
   deps = [
     "//base",
     "//components/pref_registry",