[aw] Early out zero-sized AwPicture draws

Bug: 1068864
Change-Id: I8e25de6cfa9cbe99a7aa7326650ecb871a7539a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2146550Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Tobias Sargeant <tobiasjs@chromium.org>
Commit-Queue: Tobias Sargeant <tobiasjs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758889}

android_webview/browser/gfx/aw_picture.cc

@@ -34,6 +34,9 @@ void AwPicture::Draw(JNIEnv* env,
                      const JavaParamRef<jobject>& obj,
                      const JavaParamRef<jobject>& canvas) {
   const SkIRect bounds = picture_->cullRect().roundOut();
+  if (bounds.isEmpty()) {
+    return;
+  }
   std::unique_ptr<SoftwareCanvasHolder> canvas_holder =
       SoftwareCanvasHolder::Create(canvas, gfx::Vector2d(),
                                    gfx::Size(bounds.width(), bounds.height()),