Implement difference clip rects with window rectangles

src/gpu/gl/GrGLCaps.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLCaps.h"
 
@@ skipping 445 matching lines @@
     if (fUsesMixedSamples && ctxInfo.hasExtension("GL_EXT_raster_multisample")) {
         GR_GL_GetIntegerv(gli, GR_GL_MAX_RASTER_SAMPLES, &fMaxRasterSamples);
         // This is to guard against platforms that may not support as many samples for
         // glRasterSamples as they do for framebuffers.
         fMaxStencilSampleCount = SkTMin(fMaxStencilSampleCount, fMaxRasterSamples);
     }
     fMaxColorSampleCount = fMaxStencilSampleCount;
 
     if (ctxInfo.hasExtension("GL_EXT_window_rectangles")) {
         GR_GL_GetIntegerv(gli, GR_GL_MAX_WINDOW_RECTANGLES, &fMaxWindowRectangles);
-        // Protect ourselves against tracking huge amounts of window rectangle state.
-        fMaxWindowRectangles = SkTMin(31, fMaxWindowRectangles);
     }
 
     if (kPowerVR54x_GrGLRenderer == ctxInfo.renderer() ||
         kPowerVRRogue_GrGLRenderer == ctxInfo.renderer() ||
         kAdreno3xx_GrGLRenderer == ctxInfo.renderer()) {
         fUseDrawInsteadOfClear = true;
     }
 
     if (kAdreno4xx_GrGLRenderer == ctxInfo.renderer()) {
         fUseDrawInsteadOfPartialRenderTargetWrite = true;
@@ skipping 1462 matching lines @@
 void GrGLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {
     if (options.fEnableInstancedRendering) {
         fInstancedSupport = gr_instanced::GLInstancedRendering::CheckSupport(*this);
 #ifndef SK_BUILD_FOR_MAC
         // OS X doesn't seem to write correctly to floating point textures when using
         // glDraw*Indirect, regardless of the underlying GPU.
         fAvoidInstancedDrawsToFPTargets = true;
 #endif
     }
 }