diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 710dac7..4deb815 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -247,8 +247,12 @@
     // called on the main thread in response to setPowerMode()
     void setPowerModeInternal(const sp<DisplayDevice>& hw, int mode);
 
-    void handleMessageTransaction();
-    void handleMessageInvalidate();
+    // Returns whether the transaction actually modified any state
+    bool handleMessageTransaction();
+
+    // Returns whether a new buffer has been latched (see handlePageFlip())
+    bool handleMessageInvalidate();
+
     void handleMessageRefresh();
 
     void handleTransaction(uint32_t transactionFlags);
@@ -256,10 +260,11 @@
 
     void updateCursorAsync();
 
-    /* handlePageFilp: this is were we latch a new buffer
-     * if available and compute the dirty region.
+    /* handlePageFlip - latch a new buffer if available and compute the dirty
+     * region. Returns whether a new buffer has been latched, i.e., whether it
+     * is necessary to perform a refresh during this vsync.
      */
-    void handlePageFlip();
+    bool handlePageFlip();
 
     /* ------------------------------------------------------------------------
      * Transactions