RasterModeHint should not affect restore logic

With the logic that preserves acceleration regardless of the
RasterModeHint given in ShouldAccelerate, GetOrCreateResourceProvider
will try to create a gpu resource provider even if the hint is
kPreferCPU, in which case re-creation should try to happen through
Restore() first. The hint should not have an effect on whether or not
to use Restore().

Bug: 1090180
Change-Id: Ia87b081ef611021a4c94a7ac0232c380fca3a143
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2246788Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Juanmi Huertas <juanmihd@chromium.org>
Commit-Queue: Teresa Kang <teresakang@google.com>
Cr-Commit-Position: refs/heads/master@{#778976}

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

@@ -255,15 +255,23 @@ CanvasResourceProvider* Canvas2DLayerBridge::GetOrCreateResourceProvider(
     return resource_provider;
   }
 
-  if (layer_ && !IsHibernating() && hint == RasterModeHint::kPreferGPU &&
-      acceleration_mode_ != kDisableAcceleration) {
-    return nullptr;  // re-creation will happen through restore()
-  }
+  // Restore() is tried at most four times in two seconds to recreate the
+  // ResourceProvider before the final attempt, in which a new
+  // Canvas2DLayerBridge is created along with its resource provider.
 
   bool want_acceleration = ShouldAccelerate(hint);
   RasterModeHint adjusted_hint = want_acceleration ? RasterModeHint::kPreferGPU
                                                    : RasterModeHint::kPreferCPU;
 
+  // Re-creation will happen through Restore().
+  // If the Canvas2DLayerBridge has just been created, possibly due to failed
+  // attempts of Restore(), the layer would not exist, therefore, it will not
+  // fall through this clause to try Restore() again
+  if (layer_ && !IsHibernating() &&
+      adjusted_hint == RasterModeHint::kPreferGPU) {
+    return nullptr;
+  }
+
   // We call GetOrCreateCanvasResourceProviderImpl directly here to prevent a
   // circular callstack from HTMLCanvasElement.
   resource_provider =