Make USE_OPENSSL and USE_NSS mutually exclusive

- that is, defining use_openssl=1 will now remove all dependency on NSS.

This does not impact any of the standard, non-openssl builds.

Adds stub implementations of several files that need to be fully implemented in follow up patchs.
Firefox import code will need some more substatial refactoring, as it makes little sense to be
attempting a firefox import without NSS libraries to hand, however the UI etc has numerous assumption
about the presence of this importer.

BUG=None
TEST=None

Review URL: http://codereview.chromium.org/3855004

git-svn-id: http://src.chromium.org/svn/trunk/src/build@63506 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

all.gyp

@@ -20,7 +20,6 @@
         '../jingle/jingle.gyp:*',
         '../media/media.gyp:*',
         '../net/net.gyp:*',
-        '../net/third_party/nss/ssl.gyp:*',
         '../printing/printing.gyp:*',
         '../sdch/sdch.gyp:*',
         '../skia/skia.gyp:*',
@@ -134,6 +133,11 @@
             '../remoting/remoting.gyp:*',
           ],
         }],
+        ['use_openssl!=1', {
+          'dependencies': [
+            '../net/third_party/nss/ssl.gyp:*',
+          ],
+        }],
       ],
     },
   ],

build_config.h

@@ -47,10 +47,16 @@
 
 #if defined(OS_LINUX) || defined(OS_FREEBSD) || defined(OS_OPENBSD) || \
     defined(OS_SOLARIS)
-#define USE_NSS 1  // Use NSS for crypto.
+#if !defined(USE_OPENSSL)
+#define USE_NSS 1  // Default to use NSS for crypto, unless OpenSSL is chosen.
+#endif
 #define USE_X11 1  // Use X for graphics.
 #endif
 
+#if defined(USE_OPENSSL) && defined(USE_NSS)
+#error Cannot use both OpenSSL and NSS
+#endif
+
 // For access to standard POSIXish features, use OS_POSIX instead of a
 // more specific macro.
 #if defined(OS_MACOSX) || defined(OS_LINUX) || defined(OS_FREEBSD) || \