Fix crash in Hibernate

As the ResourceProvider::snapshot() may return a nullptr, the subsequent calls
cause chrome to crash. Add checks before calling snapshot().

Bug: 991385

Change-Id: Ia00189a991afdbe8aff25d037cf02d78af376989
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1760276
Commit-Queue: Yi Xu <yiyix@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689146}

third_party/blink/renderer/platform/graphics/canvas_2d_layer_bridge.cc

@@ -240,6 +240,10 @@ void Canvas2DLayerBridge::Hibernate() {
   copy_paint.setBlendMode(SkBlendMode::kSrc);
   scoped_refptr<StaticBitmapImage> snapshot =
       resource_host_->ResourceProvider()->Snapshot();
+  if (!snapshot) {
+    logger_->ReportHibernationEvent(kHibernationAbortedDueSnapshotFailure);
+    return;
+  }
   temp_hibernation_surface->getCanvas()->drawImage(
       snapshot->PaintImageForCurrentFrame().GetSkImage(), 0, 0, &copy_paint);
   hibernation_image_ = temp_hibernation_surface->makeImageSnapshot();

third_party/blink/renderer/platform/graphics/canvas_2d_layer_bridge.h

@@ -146,11 +146,12 @@ class PLATFORM_EXPORT Canvas2DLayerBridge : public cc::TextureLayerClient {
     kHibernationAbortedDueGpuContextLoss = 4,
     kHibernationAbortedDueToSwitchToUnacceleratedRendering = 5,
     kHibernationAbortedDueToAllocationFailure = 6,
-    kHibernationEndedNormally = 7,
-    kHibernationEndedWithSwitchToBackgroundRendering = 8,
-    kHibernationEndedWithFallbackToSW = 9,
-    kHibernationEndedWithTeardown = 10,
-    kHibernationAbortedBecauseNoSurface = 11,
+    kHibernationAbortedDueSnapshotFailure = 7,
+    kHibernationEndedNormally = 8,
+    kHibernationEndedWithSwitchToBackgroundRendering = 9,
+    kHibernationEndedWithFallbackToSW = 10,
+    kHibernationEndedWithTeardown = 11,
+    kHibernationAbortedBecauseNoSurface = 12,
     kMaxValue = kHibernationAbortedBecauseNoSurface,
   };