Allow embedders to specify custom ICU data paths and command line arg…

…s. (flutter#4290)

shell/platform/embedder/embedder.cc

@@ -100,13 +100,26 @@ FlutterResult FlutterEngineRun(size_t version,
     return ptr(user_data);
   };
 
+  std::string icu_data_path;
+  if (SAFE_ACCESS(args, icu_data_path, nullptr) != nullptr) {
+    icu_data_path = SAFE_ACCESS(args, icu_data_path, nullptr);
+  }
+
+  fxl::CommandLine command_line;
+  if (SAFE_ACCESS(args, command_line_argc, 0) != 0 &&
+      SAFE_ACCESS(args, command_line_argv, nullptr) != nullptr) {
+    command_line = fxl::CommandLineFromArgcArgv(
+        SAFE_ACCESS(args, command_line_argc, 0),
+        SAFE_ACCESS(args, command_line_argv, nullptr));
+  }
+
   static std::once_flag once_shell_initialization;
   std::call_once(once_shell_initialization, [&]() {
     fxl::CommandLine null_command_line;
     shell::Shell::InitStandalone(
-        fxl::CommandLine{},
-        "",  // icu data path default lookup.
-        ""   // application library not supported in JIT mode.
+        std::move(command_line),
+        icu_data_path,  // icu data path default lookup.
+        ""              // application library not supported in JIT mode.
     );
   });
 

shell/platform/embedder/embedder.h

@@ -65,6 +65,19 @@ typedef struct {
   // after the call to |FlutterEngineRun| returns. The string must be NULL
   // terminated.
   const char* packages_path;
+  // The path to the icudtl.dat file for the project. The string can be
+  // collected after the call to |FlutterEngineRun| returns. The string must
+  // be NULL terminated.
+  const char* icu_data_path;
+  // The command line argument count used to initialize the project. The string
+  // can be collected after the call to |FlutterEngineRun| returns. The string
+  // must be NULL terminated.
+  int command_line_argc;
+  // The command line arguments used to initialize the project. The strings can
+  // be collected after the call to |FlutterEngineRun| returns. The strings must
+  // be NULL terminated.
+  const char* const* command_line_argv;
+
 } FlutterProjectArgs;
 
 typedef struct {