[merge-m49] CrOS: Don't paint tab-loading spinners in layers while in immersive fullscreen.

This regressed in r362878 which didn't handle a case where animations
occur in immersive fullscreen.

To fix, disable layer-painting of tab spinners while in fullscreen.
In most cases the tab is hidden or animating; layers shouldn't
be used. When the tab strip is fully revealed we could use layers,
but the benefit isn't worth the extra logic.

TBR=tapted@chromium.org
BUG=591535
TEST=On CrOS, enter immersive fullscreen, reload a page, reveal the
tab strip while the page is still loading, then move the mouse down
to dismiss the tab strip. Ensure a frozen throbber doesn't stick
around, floating over the page.

Review URL: https://codereview.chromium.org/1758183002

Cr-Commit-Position: refs/heads/master@{#379140}
(cherry picked from commit fde5de1bc63b656dabaafef3e5b59badcc613a22)

Review URL: https://codereview.chromium.org/1775933004 .

Cr-Commit-Position: refs/branch-heads/2623@{#604}
Cr-Branched-From: 92d77538a86529ca35f9220bd3cd512cbea1f086-refs/heads/master@{#369907}

3 files changed, 29 insertions, 2 deletions

diff --git a/chrome/browser/ui/views/frame/immersive_mode_controller_ash_unittest.cc b/chrome/browser/ui/views/frame/immersive_mode_controller_ash_unittest.cc
index f33ec1b..367b42c 100644
--- a/chrome/browser/ui/views/frame/immersive_mode_controller_ash_unittest.cc
+++ b/chrome/browser/ui/views/frame/immersive_mode_controller_ash_unittest.cc
@@ -272,6 +272,28 @@ TEST_F(ImmersiveModeControllerAshTest, TabAndBrowserFullscreen) {
   EXPECT_TRUE(controller()->ShouldHideTabIndicators());
 }
 
+// Ensure the circular tab-loading throbbers are not painted as layers in
+// immersive fullscreen, since the tab strip may animate in or out without
+// moving the layers.
+TEST_F(ImmersiveModeControllerAshTest, LayeredSpinners) {
+  AddTab(browser(), GURL("about:blank"));
+
+  TabStrip* tabstrip = browser_view()->tabstrip();
+
+  // Immersive fullscreen starts out disabled; layers are OK.
+  EXPECT_FALSE(browser_view()->GetWidget()->IsFullscreen());
+  EXPECT_FALSE(controller()->IsEnabled());
+  EXPECT_TRUE(tabstrip->CanPaintThrobberToLayer());
+
+  ToggleFullscreen();
+  EXPECT_TRUE(browser_view()->GetWidget()->IsFullscreen());
+  EXPECT_TRUE(controller()->IsEnabled());
+  EXPECT_FALSE(tabstrip->CanPaintThrobberToLayer());
+
+  ToggleFullscreen();
+  EXPECT_TRUE(tabstrip->CanPaintThrobberToLayer());
+}
+
 class ImmersiveModeControllerAshTestHostedApp
     : public ImmersiveModeControllerAshTest {
  public:
diff --git a/chrome/browser/ui/views/tabs/tab.cc b/chrome/browser/ui/views/tabs/tab.cc
index 5c95976..597c675 100644
--- a/chrome/browser/ui/views/tabs/tab.cc
+++ b/chrome/browser/ui/views/tabs/tab.cc
@@ -1479,6 +1479,7 @@ void Tab::PaintIcon(gfx::Canvas* canvas) {
 void Tab::AdvanceLoadingAnimation() {
   const TabRendererData::NetworkState state = data().network_state;
   if (controller_->IsImmersiveStyle()) {
+    throbber_->SetVisible(false);
     if (state == TabRendererData::NETWORK_STATE_WAITING) {
       // Waiting steps backwards.
       immersive_loading_step_ =
diff --git a/chrome/browser/ui/views/tabs/tab_strip.cc b/chrome/browser/ui/views/tabs/tab_strip.cc
index 56a420c..a3e1044 100644
--- a/chrome/browser/ui/views/tabs/tab_strip.cc
+++ b/chrome/browser/ui/views/tabs/tab_strip.cc
@@ -1372,9 +1372,13 @@ bool TabStrip::ShouldPaintTab(const Tab* tab, gfx::Rect* clip) {
 
 bool TabStrip::CanPaintThrobberToLayer() const {
   // Disable layer-painting of throbbers if dragging, if any tab animation is in
-  // progress, or if stacked tabs are enabled.
+  // progress, or if stacked tabs are enabled. Also disable in fullscreen: when
+  // "immersive" the tab strip could be sliding in or out while transitioning to
+  // or away from |immersive_style_| and, for other modes, there's no tab strip.
   const bool dragging = drag_controller_ && drag_controller_->started_drag();
-  return !touch_layout_ && !dragging && !IsAnimating();
+  const views::Widget* widget = GetWidget();
+  return widget && !touch_layout_ && !dragging && !IsAnimating() &&
+         !widget->IsFullscreen();
 }
 
 bool TabStrip::IsImmersiveStyle() const {