Use skia.mojom.BitmapN32 in TransferableMessage mojoms

These bitmaps are safer for transport from untrustworthy sources since
all bitmaps should be in N32 format and the browser can make bad
assumptions as a result.

R=dcheng@chromium.org

Bug: 1144462
Change-Id: Ib72a5200cce720dc42af6388d0137f5b7b1d5bb9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2572701Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Auto-Submit: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833974}

content/public/android/java/src/org/chromium/content/browser/AppWebMessagePort.java

@@ -26,7 +26,7 @@ import org.chromium.mojo.bindings.MessageReceiver;
 import org.chromium.mojo.system.Core;
 import org.chromium.mojo.system.Pair;
 import org.chromium.mojo_base.BigBufferUtil;
-import org.chromium.skia.mojom.BitmapWithArbitraryBpp;
+import org.chromium.skia.mojom.BitmapN32;
 
 /**
  * Represents the MessageChannel MessagePort object. Inspired from
@@ -299,7 +299,7 @@ public class AppWebMessagePort implements MessagePort {
         msg.message.nativeFileSystemTokens = new NativeFileSystemTransferToken[0];
         msg.message.senderOrigin = null;
         msg.arrayBufferContentsArray = new SerializedArrayBufferContents[0];
-        msg.imageBitmapContentsArray = new BitmapWithArbitraryBpp[0];
+        msg.imageBitmapContentsArray = new BitmapN32[0];
         msg.ports = ports;
         msg.streamChannels = new MessagePortDescriptor[0];
         mConnector.accept(msg.serializeWithHeader(mMojoCore, MESSAGE_HEADER));

third_party/blink/public/mojom/messaging/transferable_message.mojom

@@ -30,7 +30,7 @@ struct TransferableMessage {
   // Any ArrayBuffers being transferred as part of this message.
   array<SerializedArrayBufferContents> array_buffer_contents_array;
   // Any ImageBitmaps being transferred as part of this message.
-  array<skia.mojom.BitmapWithArbitraryBpp> image_bitmap_contents_array;
+  array<skia.mojom.BitmapN32> image_bitmap_contents_array;
   // The user activation state, null if the frame isn't providing it.
   UserActivationSnapshot? user_activation;
 };