Move some work from backend onClear to base class clear

src/gpu/GrBufferedDrawTarget.cpp

Index: src/gpu/GrBufferedDrawTarget.cpp
diff --git a/src/gpu/GrBufferedDrawTarget.cpp b/src/gpu/GrBufferedDrawTarget.cpp
index f2d9367905bb1a4f2b08fbc7e711330f72134cd7..6c144819fb489d91518b8c205b1cb15ad53ae2f4 100644
--- a/src/gpu/GrBufferedDrawTarget.cpp
+++ b/src/gpu/GrBufferedDrawTarget.cpp
@@ -81,8 +81,8 @@ void GrBufferedDrawTarget::onDrawPaths(const GrPathProcessor* pathProc,
 }
 
 void GrBufferedDrawTarget::onClear(const SkIRect* rect, GrColor color,
-                                  bool canIgnoreRect, GrRenderTarget* renderTarget) {
-    GrTargetCommands::Cmd* cmd = fCommands->recordClear(rect, color, canIgnoreRect, renderTarget);
+                                   GrRenderTarget* renderTarget) {
+    GrTargetCommands::Cmd* cmd = fCommands->recordClear(rect, color, renderTarget);
     this->recordTraceMarkersIfNecessary(cmd);
 }