Workaround for PowerVR clear issue.

BUG=skia:

Review URL: https://codereview.chromium.org/701573002
diff --git a/src/gpu/GrInOrderDrawBuffer.cpp b/src/gpu/GrInOrderDrawBuffer.cpp
index ec8972c..64d9cea 100644
--- a/src/gpu/GrInOrderDrawBuffer.cpp
+++ b/src/gpu/GrInOrderDrawBuffer.cpp
@@ -414,8 +414,8 @@
     this->recordTraceMarkersIfNecessary();
 }
 
-void GrInOrderDrawBuffer::clear(const SkIRect* rect, GrColor color,
-                                bool canIgnoreRect, GrRenderTarget* renderTarget) {
+void GrInOrderDrawBuffer::onClear(const SkIRect* rect, GrColor color,
+                                  bool canIgnoreRect, GrRenderTarget* renderTarget) {
     SkIRect r;
     if (NULL == renderTarget) {
         renderTarget = this->drawState()->getRenderTarget();