OEMCrypto Mock SRM functionality

Merge from Widevine repo of http://go/wvgerrit/24730

This CL adds SRM functionality to the modable version of oemcrypto
mock.  This can be used for end-to-end testing.

b/28955873
b/37353534

Change-Id: I2c6f513495ccfd42f7a3d7a3449db6f810563c04

libwvdrmengine/oemcrypto/mock/src/oemcrypto_key_mock.cpp

@@ -113,4 +113,9 @@ void Key::UpdateDuration(const KeyControlBlock& control) {
   control_.set_duration(control.duration());
 }
 
+void KeyControlBlock::RequireLocalDisplay() {
+  // Set all bits to require HDCP Local Display Only.
+  control_bits_ |= kControlHDCPVersionMask;
+}
+
 }  // namespace wvoec_mock