SF: Clean up around transaction commit

Rename the vague helpers for transaction commit, and getTransactionFlags
so its mutable operation is apparent. Inline superfluous variables and a
3-line function.

Bug: 182939859
Test: Build
Change-Id: I29637d0f77e8d22ce0f6ba045e4ec80274f614e8
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 60a66f4..4200be4 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -640,8 +640,12 @@
     bool isLegacyDataSpace() const;
 
     uint32_t getTransactionFlags() const { return mTransactionFlags; }
-    uint32_t getTransactionFlags(uint32_t flags);
-    uint32_t setTransactionFlags(uint32_t flags);
+
+    // Sets the masked bits.
+    void setTransactionFlags(uint32_t mask);
+
+    // Clears and returns the masked bits.
+    uint32_t clearTransactionFlags(uint32_t mask);
 
     FloatRect getBounds(const Region& activeTransparentRegion) const;
     FloatRect getBounds() const;