Mojom: Blanket change to mark all pointer/handle fields as nullable.

The purpose is to make those APIs have the same semantics as before. And
then we can selectively turn fields into non-nullable.

Mojom files that are not included in this change:
- surface-related files: the owner (jamesr) has landed some non-nullable
  fixes. It is possible that he has fully reviewed them. (I will confirm
  with him.)
- test files: have been examined.

BUG=324170
TEST=None

Review URL: https://codereview.chromium.org/502853002

Cr-Commit-Position: refs/heads/master@{#291862}

2 files changed, 9 insertions, 9 deletions

diff --git a/device/serial/data_stream.mojom b/device/serial/data_stream.mojom
index 689b381..ae64c4e 100644
--- a/device/serial/data_stream.mojom
+++ b/device/serial/data_stream.mojom
@@ -8,7 +8,7 @@ module device.serial {
 interface DataSource {
   // Initializes this DataSource with a data pipe handle to use for data
   // transmission.
-  Init(handle<data_pipe_producer> producer_handle);
+  Init(handle<data_pipe_producer>? producer_handle);
 
   // Resumes sending data after it has been stopped due to an error.
   Resume();
@@ -25,7 +25,7 @@ interface DataSourceClient {
 interface DataSink {
   // Initializes this DataSink with a data pipe handle to use for data
   // transmission.
-  Init(handle<data_pipe_consumer> consumer_handle);
+  Init(handle<data_pipe_consumer>? consumer_handle);
 
   // Requests the cancellation of any data that has been written to the pipe,
   // but has not yet been sent to the sink.
diff --git a/device/serial/serial.mojom b/device/serial/serial.mojom
index 23b12b3..a2ea53f 100644
--- a/device/serial/serial.mojom
+++ b/device/serial/serial.mojom
@@ -80,22 +80,22 @@ struct DeviceControlSignals {
 };
 
 interface SerialService {
-  GetDevices() => (DeviceInfo[] devices);
+  GetDevices() => (DeviceInfo?[]? devices);
 
   // Creates a |Connection| to |path| with options specified by |options|,
   // returning it via |connection|. This will fail and |connection| will not be
   // usable if |path| does not specify a valid serial device or there is an
   // error connecting to or configuring the connection.
-  Connect(string path,
-          ConnectionOptions options,
-          Connection& connection);
+  Connect(string? path,
+          ConnectionOptions? options,
+          Connection&? connection);
 };
 
 interface Connection {
   GetInfo() => (ConnectionInfo? info);
-  SetOptions(ConnectionOptions options) => (bool success);
-  SetControlSignals(HostControlSignals signals) => (bool success);
-  GetControlSignals() => (DeviceControlSignals signals);
+  SetOptions(ConnectionOptions? options) => (bool success);
+  SetControlSignals(HostControlSignals? signals) => (bool success);
+  GetControlSignals() => (DeviceControlSignals? signals);
   Flush() => (bool success);
 };