Update to Chromium revision fa6a5d87 (#499098)

patch/patches/supports_user_data_1710.patch

@@ -1,11 +1,11 @@
 diff --git base/supports_user_data.h base/supports_user_data.h
-index 56522e2..b945297 100644
+index 356c97329b8d..8fce524d7572 100644
 --- base/supports_user_data.h
 +++ base/supports_user_data.h
-@@ -37,9 +37,9 @@ class BASE_EXPORT SupportsUserData {
-   // Multiple user data values can be stored under different keys.
+@@ -38,9 +38,9 @@ class BASE_EXPORT SupportsUserData {
    // This object will TAKE OWNERSHIP of the given data pointer, and will
    // delete the object if it is changed or the object is destroyed.
+   // |key| must not be null--that value is too vulnerable for collision.
 -  Data* GetUserData(const void* key) const;
 -  void SetUserData(const void* key, std::unique_ptr<Data> data);
 -  void RemoveUserData(const void* key);