Add migration notification for users with Sai (#7450)

Maker has upgraded its Dai token to "Multi-Collateral Dai" (MCD) and requires
all users interacting with Dai migrate their tokens to the new version. Dai
now exclusively refers to Multi-Collateral Dai and what was previouly called
Dai is now Sai (Single Collateral Dai).

In this description, Sai refers to what was (prior to the 2019-11-18) known as Dai.
Dai is the _new_ token.

This changeset:

1. Only affects users who had non-zero Sai at the old contract address
2. Displays a persistent notification for users with Sai
3. Updates the token symbol for users already tracking the Sai token
4. Bumps our direct and indirect eth-contract-metadata dependencies

The notification copy:

> A message from Maker: The new Multi-Collateral Dai token has been released. Your old tokens are now called Sai. Please upgrade your Sai tokens to the new Dai.

The copy is from the Maker team.

app/_locales/en/messages.json

@@ -1,4 +1,10 @@
 {
+  "migrateSai": {
+    "message": "A message from Maker: The new Multi-Collateral Dai token has been released. Your old tokens are now called Sai. Please upgrade your Sai tokens to the new Dai."
+  },
+  "migrate": {
+    "message": "Migrate"
+  },
   "showIncomingTransactions": {
     "message": "Show Incoming Transactions"
   },

app/scripts/migrations/039.js

@@ -0,0 +1,67 @@
+const version = 39
+const clone = require('clone')
+const ethUtil = require('ethereumjs-util')
+
+const DAI_V1_CONTRACT_ADDRESS = '0x89d24A6b4CcB1B6fAA2625fE562bDD9a23260359'
+const DAI_V1_TOKEN_SYMBOL = 'DAI'
+const SAI_TOKEN_SYMBOL = 'SAI'
+
+function isOldDai (token = {}) {
+  return token && typeof token === 'object' &&
+    token.symbol === DAI_V1_TOKEN_SYMBOL &&
+    ethUtil.toChecksumAddress(token.address) === DAI_V1_CONTRACT_ADDRESS
+}
+
+/**
+ * This migration renames the Dai token to Sai.
+ *
+ * As of 2019-11-18 Dai is now called Sai (refs https://git.io/JeooP) to facilitate
+ * Maker's upgrade to Multi-Collateral Dai and this migration renames the token
+ * at the old address.
+ */
+module.exports = {
+  version,
+  migrate: async function (originalVersionedData) {
+    const versionedData = clone(originalVersionedData)
+    versionedData.meta.version = version
+    const state = versionedData.data
+    versionedData.data = transformState(state)
+    return versionedData
+  },
+}
+
+function transformState (state) {
+  const { PreferencesController } = state
+
+  if (PreferencesController) {
+    const tokens = PreferencesController.tokens || []
+    if (Array.isArray(tokens)) {
+      for (const token of tokens) {
+        if (isOldDai(token)) {
+          token.symbol = SAI_TOKEN_SYMBOL
+        }
+      }
+    }
+
+    const accountTokens = PreferencesController.accountTokens || {}
+    if (accountTokens && typeof accountTokens === 'object') {
+      for (const address of Object.keys(accountTokens)) {
+        const networkTokens = accountTokens[address]
+        if (networkTokens && typeof networkTokens === 'object') {
+          for (const network of Object.keys(networkTokens)) {
+            const tokensOnNetwork = networkTokens[network]
+            if (Array.isArray(tokensOnNetwork)) {
+              for (const token of tokensOnNetwork) {
+                if (isOldDai(token)) {
+                  token.symbol = SAI_TOKEN_SYMBOL
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  return state
+}

app/scripts/migrations/index.js

@@ -49,4 +49,5 @@ module.exports = [
   require('./036'),
   require('./037'),
   require('./038'),
+  require('./039'),
 ]

package.json

@@ -87,7 +87,7 @@
     "dnode": "^1.2.2",
     "end-of-stream": "^1.1.0",
     "eth-block-tracker": "^4.4.2",
-    "eth-contract-metadata": "1.9.3",
+    "eth-contract-metadata": "^1.11.0",
     "eth-ens-namehash": "^2.0.8",
     "eth-json-rpc-errors": "^1.1.0",
     "eth-json-rpc-filters": "^4.1.1",
@@ -114,7 +114,7 @@
     "extensionizer": "^1.0.1",
     "fast-json-patch": "^2.0.4",
     "fuse.js": "^3.2.0",
-    "gaba": "^1.8.0",
+    "gaba": "^1.9.0",
     "human-standard-token-abi": "^2.0.0",
     "jazzicon": "^1.2.0",
     "json-rpc-engine": "^5.1.5",