Use a mock implementation of Platform::crypto() for layout tests.

content/shell/renderer/shell_content_renderer_client.cc

Index: content/shell/renderer/shell_content_renderer_client.cc
diff --git a/content/shell/renderer/shell_content_renderer_client.cc b/content/shell/renderer/shell_content_renderer_client.cc
index a1522b9cab98e5107eb3398ac17ac42448a1d65e..657426f9150198afb88f91015626fd19da016f2d 100644
--- a/content/shell/renderer/shell_content_renderer_client.cc
+++ b/content/shell/renderer/shell_content_renderer_client.cc
@@ -170,6 +170,14 @@ WebClipboard* ShellContentRendererClient::OverrideWebClipboard() {
   return clipboard_.get();
 }
 
+WebKit::WebCrypto* ShellContentRendererClient::OverrideWebCrypto() {
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kDumpRenderTree))
+    return NULL;
+  WebTestInterfaces* interfaces =
+      ShellRenderProcessObserver::GetInstance()->test_interfaces();
+  return interfaces->crypto();
+}
+
 WebHyphenator* ShellContentRendererClient::OverrideWebHyphenator() {
   if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kDumpRenderTree))
     return NULL;