[Android] Stop hiding the RWHV layer subtree when hiding the widget

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index d61000b735e53f350cf1506e7b906a303edc8b79..2902d23a482a8875b7506ee91894d3fad6cefe6c 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -392,6 +392,7 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
       frame_evictor_(new DelegatedFrameEvictor(this)),
       locks_on_frame_count_(0),
       observing_root_window_(false),
+      should_unlock_surface_on_visibility_lost_or_activity_resumed_(false),
       weak_ptr_factory_(this) {
   host_->SetView(this);
   SetContentViewCore(content_view_core);
@@ -708,6 +709,7 @@ void RenderWidgetHostViewAndroid::OnShowUnhandledTapUIIfNeeded(int x_dip,
 }
 
 void RenderWidgetHostViewAndroid::ReleaseLocksOnSurface() {
+  should_unlock_surface_on_visibility_lost_or_activity_resumed_ = false;
   if (!frame_evictor_->HasFrame()) {
     DCHECK_EQ(locks_on_frame_count_, 0u);
     return;
@@ -1881,6 +1883,17 @@ void RenderWidgetHostViewAndroid::OnDetachCompositor() {
   overscroll_controller_.reset();
 }
 
+void RenderWidgetHostViewAndroid::OnVisibilityChanged(bool visible) {
+  if (visible)

[jdduke (slow), 2015/03/16 16:54:12]

We never see this callback, as we stop observing the window when we're hidden.

[no sievers, 2015/03/17 21:37:47]

Maybe that's ok. If somebody called Hide() we already dropped everything and
shouldn't be visible anymore.

+    return;
+
+  if (should_unlock_surface_on_visibility_lost_or_activity_resumed_) {

[no sievers, 2015/03/17 21:37:47]

nit: maybe |surface_locked_for_paused_activity_| or so?

+    should_unlock_surface_on_visibility_lost_or_activity_resumed_ = false;
+    DCHECK_GT(locks_on_frame_count_, 0U);
+    UnlockCompositingSurface();
+  }
+}
+
 void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
                                           base::TimeDelta vsync_period) {
   TRACE_EVENT0("cc,benchmark", "RenderWidgetHostViewAndroid::OnVSync");
@@ -1907,6 +1920,22 @@ void RenderWidgetHostViewAndroid::OnAnimate(base::TimeTicks begin_frame_time) {
     SetNeedsAnimate();
 }
 
+void RenderWidgetHostViewAndroid::OnActivityResumed() {
+  if (should_unlock_surface_on_visibility_lost_or_activity_resumed_) {
+    should_unlock_surface_on_visibility_lost_or_activity_resumed_ = false;
+    DCHECK_GT(locks_on_frame_count_, 0U);
+    UnlockCompositingSurface();
+  }
+}
+
+void RenderWidgetHostViewAndroid::OnActivityPaused() {
+  if (IsShowing()) {
+    DCHECK(!should_unlock_surface_on_visibility_lost_or_activity_resumed_);
+    should_unlock_surface_on_visibility_lost_or_activity_resumed_ = true;
+    LockCompositingSurface();
+  }
+}
+
 void RenderWidgetHostViewAndroid::OnLostResources() {
   ReleaseLocksOnSurface();
   if (layer_.get())