Adding hasPendingCommands API method to SkDeferredCanvas

BUG=http://code.google.com/p/chromium/issues/detail?id=146178
Review URL: https://codereview.appspot.com/6550050

git-svn-id: http://skia.googlecode.com/svn/trunk@5632 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/utils/SkDeferredCanvas.h b/include/utils/SkDeferredCanvas.h
index f3005b3..f5674d1 100644
--- a/include/utils/SkDeferredCanvas.h
+++ b/include/utils/SkDeferredCanvas.h
@@ -87,6 +87,12 @@
     bool isFreshFrame() const;
 
     /**
+     *  Returns true if the canvas has recorded draw commands that have
+     *  not yet been played back.
+     */
+    bool hasPendingCommands() const;
+
+    /**
      *  Specify the maximum number of bytes to be allocated for the purpose
      *  of recording draw commands to this canvas.  The default limit, is
      *  64MB.