Fixes a bug when the framebuffer is cleared with invalid scissor rect

cc/direct_renderer.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/direct_renderer.h"
 
 #include <vector>
 
 #include "base/debug/trace_event.h"
 #include "base/metrics/histogram.h"
@@ skipping 222 matching lines @@
         return;
 
     bool usingScissorAsOptimization = capabilities().usingPartialSwap;
     gfx::RectF renderPassScissor;
 
     if (usingScissorAsOptimization) {
         renderPassScissor = computeScissorRectForRenderPass(frame);
         setScissorTestRect(moveScissorToWindowSpace(frame, renderPassScissor));
     }
 
-    if (frame.currentRenderPass != frame.rootRenderPass || m_client->shouldClearRootRenderPass())
+    if (frame.currentRenderPass != frame.rootRenderPass || m_client->shouldClearRootRenderPass()) {
+        if (!usingScissorAsOptimization)
+            ensureScissorTestDisabled();
         clearFramebuffer(frame);
+    }
 
     const QuadList& quadList = renderPass->quad_list;
     for (QuadList::constBackToFrontIterator it = quadList.backToFrontBegin(); it != quadList.backToFrontEnd(); ++it) {
         const DrawQuad& quad = *(*it);
         bool shouldSkipQuad = false;
 
         if (usingScissorAsOptimization)
             setScissorStateForQuadWithRenderPassScissor(frame, quad, renderPassScissor, &shouldSkipQuad);
         else
             setScissorStateForQuad(frame, quad);
@@ skipping 43 matching lines @@
     return pass->output_rect.size();
 }
 
 // static
 GLenum DirectRenderer::renderPassTextureFormat(const RenderPass*)
 {
     return GL_RGBA;
 }
 
 }  // namespace cc