Revert "Update mojo sdk to rev 8d45c89c30b230843c5bd6dd0693a555750946c0"

third_party/mojo/src/mojo/public/c/system/buffer.h

Index: third_party/mojo/src/mojo/public/c/system/buffer.h
diff --git a/third_party/mojo/src/mojo/public/c/system/buffer.h b/third_party/mojo/src/mojo/public/c/system/buffer.h
index 45d2c2d761fb32d86a39a80c77b7b14584b35c11..97bc340f04b1e378d5faaadf874cc1352651545b 100644
--- a/third_party/mojo/src/mojo/public/c/system/buffer.h
+++ b/third_party/mojo/src/mojo/public/c/system/buffer.h
@@ -169,9 +169,9 @@ MOJO_SYSTEM_EXPORT MojoResult MojoMapBuffer(MojoHandle buffer_handle,
                                             MojoMapBufferFlags flags);
 
 // Unmaps a buffer pointer that was mapped by |MojoMapBuffer()|. |buffer| must
-// have been the result of |MojoMapBuffer()| (not some other pointer inside
+// have been the result of |MojoMapBuffer()| (not some pointer strictly inside
 // the mapped memory), and the entire mapping will be removed (partial unmapping
-// is not supported). A mapping may only be unmapped once.
+// is not supported). A mapping may only be unmapped exactly once.
 //
 // Returns:
 //   |MOJO_RESULT_OK| on success.