cc: Call PrepareTiles when becoming visible in browser only.

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 6d9c9c67199fbe1de37c8e323c741e004d8b6798..29a809535783bc03295f9f0ce76116214a69df62 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -272,6 +272,35 @@ class LayerTreeHostTestReadyToDrawNonEmpty
 // single threaded mode.
 SINGLE_THREAD_TEST_F(LayerTreeHostTestReadyToDrawNonEmpty);
 
+// This tests that we get the ready to draw signal eventually even if we become
+// invisible and then become visible again.
+class LayerTreeHostTestReadyToDrawVisibility
+    : public LayerTreeHostTestReadyToDrawNonEmpty {
+ public:
+  LayerTreeHostTestReadyToDrawVisibility()
+      : LayerTreeHostTestReadyToDrawNonEmpty(), did_commit_(false) {}
+
+  void CommitCompleteOnThread(LayerTreeHostImpl* host_impl) override {
+    EXPECT_FALSE(did_commit_);
+    did_commit_ = true;
+    PostSetVisibleToMainThread(false);
+  }
+
+  void DidSetVisibleOnImplTree(LayerTreeHostImpl* host_impl,
+                               bool visible) override {
+    if (!visible) {
+      EXPECT_TRUE(did_commit_);
+      EXPECT_FALSE(did_notify_ready_to_draw_);
+      PostSetVisibleToMainThread(true);
+    }
+  }
+
+ protected:
+  bool did_commit_;
+};
+
+SINGLE_THREAD_TEST_F(LayerTreeHostTestReadyToDrawVisibility);
+
 class LayerTreeHostFreeWorkerContextResourcesTest : public LayerTreeHostTest {
  public:
   scoped_ptr<FakeOutputSurface> CreateFakeOutputSurface() override {