Add a "disabled" field for GPU Blacklist entries.

content/browser/gpu/gpu_data_manager.cc

Index: content/browser/gpu/gpu_data_manager.cc
===================================================================
--- content/browser/gpu/gpu_data_manager.cc	(revision 101518)
+++ content/browser/gpu/gpu_data_manager.cc	(working copy)
@@ -422,6 +422,16 @@
     }
   }
 
+  // This counts how many users are affected by a disabled entry - this allows
+  // us to understand the impact of an entry before enable it.
+  std::vector<uint32> flag_disabled_entries;
+  gpu_blacklist->GetGpuFeatureFlagDisabledEntries(
+      GpuFeatureFlags::kGpuFeatureAll, flag_disabled_entries);
+  for (size_t i = 0; i < flag_disabled_entries.size(); ++i) {
+    UMA_HISTOGRAM_ENUMERATION("GPU.BlacklistTestResultsPerDisabledEntry",
+        flag_disabled_entries[i], max_entry_id + 1);
+  }
+
   const GpuFeatureFlags::GpuFeatureType kGpuFeatures[] = {
       GpuFeatureFlags::kGpuFeatureAccelerated2dCanvas,
       GpuFeatureFlags::kGpuFeatureAcceleratedCompositing,