Snap layer bounds to pixel boundaries.

Change-Id: I272ceebf469a119f01ea9d73cdd68519afdffa99

libs/hwui/OpenGLRenderer.cpp

@@ -353,6 +353,8 @@ bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top,
 
     // Layers only make sense if they are in the framebuffer's bounds
     bounds.intersect(*mSnapshot->clipRect);
+    bounds.snapToPixelBoundaries();
+
     if (bounds.isEmpty() || bounds.getWidth() > mMaxTextureSize ||
             bounds.getHeight() > mMaxTextureSize) {
         return false;

libs/hwui/Rect.h

@@ -148,6 +148,13 @@ struct Rect {
         return false;
     }
 
+    void snapToPixelBoundaries() {
+        left = floor(left);
+        top = floor(top);
+        right = ceil(right);
+        bottom = ceil(bottom);
+    }
+
     void dump() const {
         LOGD("Rect[l=%f t=%f r=%f b=%f]", left, top, right, bottom);
     }