Adding functionality for purgin graphics resource handles
This will allow a fix to WebKit for preventing a crash when the graphics
context is destroyed before the GrContext

BUG=http://code.google.com/p/chromium/issues/detail?id=85309



git-svn-id: http://skia.googlecode.com/svn/trunk@1551 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/include/GrContext.h b/gpu/include/GrContext.h
index 58c53ba..8809271 100644
--- a/gpu/include/GrContext.h
+++ b/gpu/include/GrContext.h
@@ -66,6 +66,13 @@
     void contextLost();
 
     /**
+     * Similar to contextLost, but makes no attempt to reset state.
+     * Use this method when GrContext destruction is pending, but
+     * the graphics context is destroyed first.
+     */
+    void contextDestroyed();
+
+    /**
      * Frees gpu created by the context. Can be called to reduce GPU memory
      * pressure.
      */