Suspend SVG image animations when the page is hidden

Check Document::hidden() in LayoutObject::WillRenderImage,
thus pausing animations on pages that are not visible.
To resume animations, we may need to explicitly resume the
timeline, so a hook is added in Page::SetVisibilityState to
allow calling StartAnimation() on the relevant SVGImages.

Bug: 856082
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I4a0b008730ec3e6c2af26e15d52eebb26020ad32
Reviewed-on: https://chromium-review.googlesource.com/1115130Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#571543}

third_party/blink/renderer/core/layout/layout_object.cc

@@ -3518,6 +3518,10 @@ bool LayoutObject::WillRenderImage() {
   if (GetDocument().IsContextPaused())
     return false;
 
+  // Suspend animations when the page is not visible.
+  if (GetDocument().hidden())
+    return false;
+
   // If we're not in a window (i.e., we're dormant from being in a background
   // tab) then we don't want to render either.
   return GetDocument().View()->IsVisible();

third_party/blink/renderer/core/page/page.cc

@@ -66,6 +66,7 @@
 #include "third_party/blink/renderer/core/paint/paint_layer.h"
 #include "third_party/blink/renderer/core/paint/paint_layer_scrollable_area.h"
 #include "third_party/blink/renderer/core/probe/core_probes.h"
+#include "third_party/blink/renderer/core/svg/graphics/svg_image_chrome_client.h"
 #include "third_party/blink/renderer/platform/graphics/graphics_layer.h"
 #include "third_party/blink/renderer/platform/loader/fetch/resource_fetcher.h"
 #include "third_party/blink/renderer/platform/plugins/plugin_data.h"
@@ -345,6 +346,14 @@ void Page::ResetPluginData() {
   }
 }
 
+static void RestoreSVGImageAnimations() {
+  for (const Page* page : AllPages()) {
+    if (auto* svg_image_chrome_client =
+            ToSVGImageChromeClientOrNull(page->GetChromeClient()))
+      svg_image_chrome_client->RestoreAnimationIfNeeded();
+  }
+}
+
 void Page::SetValidationMessageClient(ValidationMessageClient* client) {
   validation_message_client_ = client;
 }
@@ -456,11 +465,15 @@ void Page::SetVisibilityState(mojom::PageVisibilityState visibility_state,
     return;
   visibility_state_ = visibility_state;
 
-  if (!is_initial_state)
+  if (is_initial_state)
+    return;
   NotifyPageVisibilityChanged();
 
-  if (!is_initial_state && main_frame_)
+  if (main_frame_) {
+    if (IsPageVisible())
+      RestoreSVGImageAnimations();
     main_frame_->DidChangeVisibilityState();
+  }
 }
 
 mojom::PageVisibilityState Page::VisibilityState() const {

third_party/blink/renderer/core/svg/graphics/svg_image.cc

@@ -593,6 +593,17 @@ void SVGImage::ResetAnimation() {
   ScheduleTimelineRewind();
 }
 
+void SVGImage::RestoreAnimation() {
+  // If the image has no animations then do nothing.
+  if (!MaybeAnimated())
+    return;
+  // If there are no clients, or no client is going to render, then do nothing.
+  ImageObserver* image_observer = GetImageObserver();
+  if (!image_observer || image_observer->ShouldPauseAnimation(this))
+    return;
+  StartAnimation();
+}
+
 bool SVGImage::MaybeAnimated() {
   SVGSVGElement* root_element = SvgRootElement(page_.Get());
   if (!root_element)

third_party/blink/renderer/core/svg/graphics/svg_image.h

@@ -73,6 +73,7 @@ class CORE_EXPORT SVGImage final : public Image {
 
   void StartAnimation() override;
   void ResetAnimation() override;
+  void RestoreAnimation();
 
   PaintImage::CompletionState completion_state() const {
     return load_state_ == LoadState::kLoadCompleted

third_party/blink/renderer/core/svg/graphics/svg_image_chrome_client.cc

@@ -91,6 +91,13 @@ void SVGImageChromeClient::ResumeAnimation() {
   ScheduleAnimation(nullptr);
 }
 
+void SVGImageChromeClient::RestoreAnimationIfNeeded() {
+  // If the timeline is not suspended we needn't attempt to restore.
+  if (!IsSuspended())
+    return;
+  image_->RestoreAnimation();
+}
+
 void SVGImageChromeClient::ScheduleAnimation(const LocalFrameView*) {
   // Because a single SVGImage can be shared by multiple pages, we can't key
   // our svg image layout on the page's real animation frame. Therefore, we
@@ -105,7 +112,7 @@ void SVGImageChromeClient::ScheduleAnimation(const LocalFrameView*) {
   // stringent.
   double fire_time = 0;
   if (image_->MaybeAnimated()) {
-    if (timeline_state_ >= kSuspended)
+    if (IsSuspended())
       return;
     fire_time = kAnimationFrameDelay;
   }

third_party/blink/renderer/core/svg/graphics/svg_image_chrome_client.h

@@ -49,6 +49,8 @@ class CORE_EXPORT SVGImageChromeClient final : public EmptyChromeClient {
 
   void SuspendAnimation();
   void ResumeAnimation();
+  void RestoreAnimationIfNeeded();
+
   bool IsSuspended() const { return timeline_state_ >= kSuspended; }
 
  private:
@@ -59,6 +61,7 @@ class CORE_EXPORT SVGImageChromeClient final : public EmptyChromeClient {
   void ScheduleAnimation(const LocalFrameView*) override;
 
   void SetTimer(std::unique_ptr<TimerBase>);
+  TimerBase* GetTimerForTesting() const { return animation_timer_.get(); }
   void AnimationTimerFired(TimerBase*);
 
   SVGImage* image_;
@@ -71,6 +74,8 @@ class CORE_EXPORT SVGImageChromeClient final : public EmptyChromeClient {
 
   FRIEND_TEST_ALL_PREFIXES(SVGImageTest, TimelineSuspendAndResume);
   FRIEND_TEST_ALL_PREFIXES(SVGImageTest, ResetAnimation);
+  FRIEND_TEST_ALL_PREFIXES(SVGImagePageVisibilityTest,
+                           PageVisibilityHiddenToVisible);
 };
 
 DEFINE_TYPE_CASTS(SVGImageChromeClient,

third_party/blink/renderer/core/svg/graphics/svg_image_test.cc

@@ -11,9 +11,12 @@
 #include "third_party/blink/public/platform/scheduler/test/renderer_scheduler_test_support.h"
 #include "third_party/blink/renderer/core/frame/local_frame_view.h"
 #include "third_party/blink/renderer/core/frame/visual_viewport.h"
+#include "third_party/blink/renderer/core/html/html_image_element.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/core/paint/paint_layer.h"
 #include "third_party/blink/renderer/core/svg/graphics/svg_image_chrome_client.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_request.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_test.h"
 #include "third_party/blink/renderer/platform/geometry/float_rect.h"
 #include "third_party/blink/renderer/platform/graphics/paint/paint_canvas.h"
 #include "third_party/blink/renderer/platform/graphics/paint/paint_flags.h"
@@ -194,4 +197,56 @@ TEST_F(SVGImageTest, SetSizeOnVisualViewport) {
             GetImage().GetPageForTesting()->GetVisualViewport().Size());
 }
 
+class SVGImagePageVisibilityTest : public SimTest {};
+
+TEST_F(SVGImagePageVisibilityTest, PageVisibilityHiddenToVisible) {
+  SimRequest main_resource("https://example.com/", "text/html");
+  SimRequest image_resource("https://example.com/image.svg", "image/svg+xml");
+  LoadURL("https://example.com/");
+  main_resource.Complete("<img src='image.svg' width='100' id='image'>");
+  image_resource.Complete(kAnimatedDocument);
+
+  Compositor().BeginFrame();
+
+  Element* element = GetDocument().getElementById("image");
+  ASSERT_TRUE(IsHTMLImageElement(element));
+
+  ImageResourceContent* image_content =
+      ToHTMLImageElement(*element).CachedImage();
+  ASSERT_TRUE(image_content);
+  ASSERT_TRUE(image_content->IsLoaded());
+  ASSERT_TRUE(image_content->HasImage());
+  Image* image = image_content->GetImage();
+  ASSERT_TRUE(image->IsSVGImage());
+  SVGImageChromeClient& svg_image_chrome_client =
+      ToSVGImage(*image).ChromeClientForTesting();
+  TimerBase* timer = svg_image_chrome_client.GetTimerForTesting();
+
+  // Wait for the next animation frame to be triggered, and then trigger a new
+  // frame. The image animation timeline should be running.
+  test::RunDelayedTasks(TimeDelta::FromMilliseconds(1) +
+                        TimeDelta::FromSecondsD(timer->NextFireInterval()));
+  Compositor().BeginFrame();
+
+  EXPECT_FALSE(svg_image_chrome_client.IsSuspended());
+
+  // Set page visibility to 'hidden', and then wait for the animation timer to
+  // fire. This should suspend the image animation. (Suspend the image's
+  // animation timeline.)
+  WebView().SetVisibilityState(mojom::PageVisibilityState::kHidden, false);
+  test::RunDelayedTasks(TimeDelta::FromMilliseconds(1) +
+                        TimeDelta::FromSecondsD(timer->NextFireInterval()));
+
+  EXPECT_TRUE(svg_image_chrome_client.IsSuspended());
+
+  // Set page visibility to 'visible' - this should schedule a new animation
+  // frame and resume the image animation.
+  WebView().SetVisibilityState(mojom::PageVisibilityState::kVisible, false);
+  test::RunDelayedTasks(TimeDelta::FromMilliseconds(1) +
+                        TimeDelta::FromSecondsD(timer->NextFireInterval()));
+  Compositor().BeginFrame();
+
+  EXPECT_FALSE(svg_image_chrome_client.IsSuspended());
+}
+
 }  // namespace blink