ODK and Shared Libraries

In this code drop we introduce the ODK dependency. The reference
implementation has been updated to make use of the ODK and the related
tests have been included.

In addition, we have included an example of how a shared libraries can
be created. This will allow make it easier to test and verify different
implementations of the API.

Most other changes introduce by this code drop were made to clean-up the
reference implementation and limit dependencies.

chromium_deps/cdm/protos/defs/license_protocol.proto

@@ -111,6 +111,13 @@ message License {
     // Enables "soft enforcement" of playback_duration_seconds, letting the user
     // finish playback even if short window expires. Optional.
     optional bool soft_enforce_playback_duration = 14 [default = false];
+
+    // Enables "soft enforcement" of rental_duration_seconds. Initial playback
+    // must always start before rental duration expires.  In order to allow
+    // subsequent playbacks to start after the rental duration expires,
+    // soft_enforce_playback_duration must be true. Otherwise, subsequent
+    // playbacks will not be allowed once rental duration expires. Optional.
+    optional bool soft_enforce_rental_duration = 15 [default = true];
   }
   // LINT.ThenChange(//depot/google3/google/chrome/widevine/licensedata/v1/license_policy.proto)