Use BoringSSL's forward declaration header.

This avoids depending on the name of the C struct. BoringSSL already
provides a header with forward declarations.

Change-Id: I0187f4c51c674746d5926b372ab48ea0e72eae4e
Reviewed-on: https://chromium-review.googlesource.com/c/1287044Reviewed-by: Joe Downing <joedow@chromium.org>
Reviewed-by: Steven Valdez <svaldez@chromium.org>
Commit-Queue: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606923}

crypto/signature_creator.h

@@ -13,9 +13,7 @@
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "crypto/crypto_export.h"
-
-// Forward declaration for openssl/*.h
-typedef struct env_md_ctx_st EVP_MD_CTX;
+#include "third_party/boringssl/src/include/openssl/base.h"
 
 namespace crypto {
 

net/cert/ct_log_verifier.h

@@ -12,10 +12,7 @@
 #include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 #include "net/cert/signed_certificate_timestamp.h"
-
-// Forward declare the crypto types to avoid having to include the full
-// headers.
-typedef struct evp_pkey_st EVP_PKEY;
+#include "third_party/boringssl/src/include/openssl/base.h"
 
 namespace net {
 

remoting/protocol/spake2_authenticator.h

@@ -14,8 +14,7 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "remoting/protocol/authenticator.h"
-
-typedef struct spake2_ctx_st SPAKE2_CTX;
+#include "third_party/boringssl/src/include/openssl/base.h"
 
 namespace remoting {