WIP Notifying buffers of head text change

Co-Authored-By: Mikayla Maki <mikayla@zed.dev>

crates/editor/src/multi_buffer.rs

@@ -312,13 +312,13 @@ impl MultiBuffer {
         self.read(cx).symbols_containing(offset, theme)
     }
 
-    pub fn update_git(&mut self, cx: &mut ModelContext<Self>) {
+    pub fn git_diff_recalc(&mut self, cx: &mut ModelContext<Self>) {
         let buffers = self.buffers.borrow();
         for buffer_state in buffers.values() {
-            if buffer_state.buffer.read(cx).needs_git_update() {
+            if buffer_state.buffer.read(cx).needs_git_diff_recalc() {
                 buffer_state
                     .buffer
-                    .update(cx, |buffer, cx| buffer.update_git(cx))
+                    .update(cx, |buffer, cx| buffer.git_diff_recalc(cx))
             }
         }
     }