Move some work from backend onClear to base class clear

src/gpu/gl/GrGLGpu.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLGpu.h"
 #include "GrGLGLSL.h"
@@ skipping 1551 matching lines @@
 }
 
 void GrGLGpu::disableScissor() {
     if (kNo_TriState != fHWScissorSettings.fEnabled) {
         GL_CALL(Disable(GR_GL_SCISSOR_TEST));
         fHWScissorSettings.fEnabled = kNo_TriState;
         return;
     }
 }
 
-void GrGLGpu::onClear(GrRenderTarget* target, const SkIRect* rect, GrColor color,
-                      bool canIgnoreRect) {
+void GrGLGpu::onClear(GrRenderTarget* target, const SkIRect& rect, GrColor color) {
     // parent class should never let us get here with no RT
     SkASSERT(target);
     GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(target);
 
-    if (canIgnoreRect && this->glCaps().fullClearIsFree()) {
-        rect = NULL;
-    }
-
-    SkIRect clippedRect;
-    if (rect) {
-        // flushScissor expects rect to be clipped to the target.
-        clippedRect = *rect;
-        SkIRect rtRect = SkIRect::MakeWH(target->width(), target->height());
-        if (clippedRect.intersect(rtRect)) {
-            rect = &clippedRect;
-        } else {
-            return;
-        }
-    }
-
-    this->flushRenderTarget(glRT, rect);
+    this->flushRenderTarget(glRT, &rect);
     GrScissorState scissorState;
-    if (rect) {
-        scissorState.set(*rect);
-    }
+    scissorState.set(rect);
     this->flushScissor(scissorState, glRT->getViewport(), glRT->origin());
 
     GrGLfloat r, g, b, a;
     static const GrGLfloat scale255 = 1.f / 255.f;
     a = GrColorUnpackA(color) * scale255;
     GrGLfloat scaleRGB = scale255;
     r = GrColorUnpackR(color) * scaleRGB;
     g = GrColorUnpackG(color) * scaleRGB;
     b = GrColorUnpackB(color) * scaleRGB;
 
@@ skipping 1604 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }