Include EXT_window_rectangles API

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index ea02d21c90e46332c215e68da2388535938049f4..2c9990fa257380c2c03039bf0cd62dc437d4959d 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -462,6 +462,12 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
     }
     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()) {