Tell Skia memory dump not to dump wrapped/external GPU objects

Skia currently dumps wrapped objects, and Chrome tries to alias these
objects with Chrome's own dumps. This isn't always possible, so instead
this change uses a new Skia API to ask Skia to skip dumping these.

Bug: 795358
Change-Id: Iee3dbbb09037cb84fa8a33f0512cb2a54ef42f32
Reviewed-on: https://chromium-review.googlesource.com/979773Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545820}

services/ui/public/cpp/gpu/context_provider_command_buffer.cc

@@ -112,6 +112,12 @@ class SkiaGpuTraceMemoryDump : public SkTraceMemoryDump {
     return kObjectsBreakdowns_LevelOfDetail;
   }
 
+  bool shouldDumpWrappedObjects() const override {
+    // Chrome already dumps objects it imports into Skia. Avoid duplicate dumps
+    // by asking Skia not to dump them.
+    return false;
+  }
+
  private:
   // Helper to create allocator dumps.
   base::trace_event::MemoryAllocatorDump* GetOrCreateAllocatorDump(