Mojo: Replace MessageInTransit::Header's data_size with total_size.

R=yzshen@chromium.org

Review URL: https://codereview.chromium.org/180423003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253324 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 10 insertions, 5 deletions

diff --git a/mojo/system/message_in_transit.cc b/mojo/system/message_in_transit.cc
index 3b7f315..8ab1148 100644
--- a/mojo/system/message_in_transit.cc
+++ b/mojo/system/message_in_transit.cc
@@ -54,7 +54,10 @@ MessageInTransit::MessageInTransit(OwnedBuffer,
   DCHECK_LE(num_bytes, kMaxMessageNumBytes);
   DCHECK_LE(num_handles, kMaxMessageNumHandles);
 
-  header()->data_size = num_bytes;
+  // Note: If dispatchers are subsequently attached (in particular, if
+  // |num_handles| is nonzero), then |total_size| will have to be adjusted.
+  // TODO(vtl): Figure out where we should really set this.
+  header()->total_size = static_cast<uint32_t>(main_buffer_size_);
   header()->type = type;
   header()->subtype = subtype;
   header()->source_id = kInvalidEndpointId;
@@ -138,8 +141,8 @@ bool MessageInTransit::GetNextMessageSize(const void* buffer,
     return false;
 
   const Header* header = static_cast<const Header*>(buffer);
-  *next_message_size =
-      RoundUpMessageAlignment(sizeof(Header) + header->data_size);
+  *next_message_size = header->total_size;
+  DCHECK_EQ(*next_message_size % kMessageAlignment, 0u);
   return true;
 }
 
diff --git a/mojo/system/message_in_transit.h b/mojo/system/message_in_transit.h
index eda0963..b3ac389 100644
--- a/mojo/system/message_in_transit.h
+++ b/mojo/system/message_in_transit.h
@@ -153,8 +153,10 @@ class MOJO_SYSTEM_IMPL_EXPORT MessageInTransit {
   // "Header" for the data. Must be a multiple of |kMessageAlignment| bytes in
   // size. Must be POD.
   struct Header {
-    // Total size of data following the "header".
-    uint32_t data_size;
+    // Total size of the message, including the header, the message data
+    // ("bytes") including padding (to make it a multiple of |kMessageAlignment|
+    // bytes), and serialized handle information (TODO(vtl)).
+    uint32_t total_size;
     Type type;
     Subtype subtype;
     EndpointId source_id;