Allow user to specify which Chrome binary to use. (#53275)

* Allow user to specify which Chrome binary to use.

packages/flutter_tools/lib/src/commands/drive.dart

@@ -108,7 +108,10 @@ class DriveCommand extends RunCommandBase {
       ..addFlag('android-emulator',
         defaultsTo: true,
         help: 'Whether to perform Flutter Driver testing on Android Emulator.'
-          'Works only if \'browser-name\' is set to \'android-chrome\'');
+          'Works only if \'browser-name\' is set to \'android-chrome\'')
+      ..addOption('chrome-binary',
+        help: 'Location of Chrome binary. '
+          'Works only if \'browser-name\' is set to \'chrome\'');
   }
 
   @override
@@ -245,6 +248,7 @@ class DriveCommand extends RunCommandBase {
           driverPort,
           browser,
           argResults['headless'].toString() == 'true',
+          stringArg('chrome-binary'),
         );
       } on Exception catch (ex) {
         throwToolExit(
@@ -529,17 +533,18 @@ Browser _browserNameToEnum(String browserName){
   throw UnsupportedError('Browser $browserName not supported');
 }
 
-Future<async_io.WebDriver> _createDriver(String driverPort, Browser browser, bool headless) async {
+Future<async_io.WebDriver> _createDriver(String driverPort, Browser browser, bool headless, String chromeBinary) async {
   return async_io.createDriver(
       uri: Uri.parse('http://localhost:$driverPort/'),
-      desired: getDesiredCapabilities(browser, headless),
+      desired: getDesiredCapabilities(browser, headless, chromeBinary),
       spec: async_io.WebDriverSpec.Auto
   );
 }
 
-/// Returns desired capabilities for given [browser] and [headless].
+/// Returns desired capabilities for given [browser], [headless] and
+/// [chromeBinary].
 @visibleForTesting
-Map<String, dynamic> getDesiredCapabilities(Browser browser, bool headless) {
+Map<String, dynamic> getDesiredCapabilities(Browser browser, bool headless, [String chromeBinary]) {
   switch (browser) {
     case Browser.chrome:
       return <String, dynamic>{
@@ -547,6 +552,8 @@ Map<String, dynamic> getDesiredCapabilities(Browser browser, bool headless) {
         'browserName': 'chrome',
         'goog:loggingPrefs': <String, String>{ async_io.LogType.performance: 'ALL'},
         'chromeOptions': <String, dynamic>{
+          if (chromeBinary != null)
+            'binary': chromeBinary,
           'w3c': false,
           'args': <String>[
             '--bwsi',
@@ -566,7 +573,7 @@ Map<String, dynamic> getDesiredCapabilities(Browser browser, bool headless) {
                 'v8,blink.console,benchmark,blink,'
                 'blink.user_timing'
           }
-        }
+        },
       };
       break;
     case Browser.firefox:

packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart

@@ -612,11 +612,13 @@ void main() {
     });
 
     test('Chrome with headless off', () {
+      const String chromeBinary = 'random-binary';
       final Map<String, dynamic> expected = <String, dynamic>{
         'acceptInsecureCerts': true,
         'browserName': 'chrome',
         'goog:loggingPrefs': <String, String>{ sync_io.LogType.performance: 'ALL'},
         'chromeOptions': <String, dynamic>{
+          'binary': chromeBinary,
           'w3c': false,
           'args': <String>[
             '--bwsi',
@@ -638,7 +640,7 @@ void main() {
         }
       };
 
-      expect(getDesiredCapabilities(Browser.chrome, false), expected);
+      expect(getDesiredCapabilities(Browser.chrome, false, chromeBinary), expected);
 
     });