Add "create_bundle" target in order to support bundle with gn.

tools/gn/function_toolchain.cc

Index: tools/gn/function_toolchain.cc
diff --git a/tools/gn/function_toolchain.cc b/tools/gn/function_toolchain.cc
index 9eeae982cf3bf17210ef53e4325d23b69c7f98a1..5dac19ae4b129676487d07f003d88b8a934eeb45 100644
--- a/tools/gn/function_toolchain.cc
+++ b/tools/gn/function_toolchain.cc
@@ -812,9 +812,13 @@ Value RunTool(Scope* scope,
   } else if (IsLinkerTool(tool_type)) {
     subst_validator = &IsValidLinkerSubstitution;
     subst_output_validator = &IsValidLinkerOutputsSubstitution;
-  } else if (tool_type == Toolchain::TYPE_COPY) {
+  } else if (tool_type == Toolchain::TYPE_COPY ||
+             tool_type == Toolchain::TYPE_COPY_BUNDLE_DATA) {
     subst_validator = &IsValidCopySubstitution;
     subst_output_validator = &IsValidCopySubstitution;
+  } else if (tool_type == Toolchain::TYPE_COMPILE_XCASSETS) {
+    subst_validator = &IsValidCompileXCassetsSubstitution;
+    subst_output_validator = &IsValidCompileXCassetsSubstitution;
   } else {
     subst_validator = &IsValidToolSubstitution;
     subst_output_validator = &IsValidToolSubstitution;
@@ -851,7 +855,10 @@ Value RunTool(Scope* scope,
     return Value();
   }
 
-  if (tool_type != Toolchain::TYPE_COPY && tool_type != Toolchain::TYPE_STAMP) {
+  if (tool_type != Toolchain::TYPE_COPY &&
+      tool_type != Toolchain::TYPE_STAMP &&
+      tool_type != Toolchain::TYPE_COPY_BUNDLE_DATA &&
+      tool_type != Toolchain::TYPE_COMPILE_XCASSETS) {
     // All tools except the copy and stamp tools should have outputs. The copy
     // and stamp tool's outputs are generated internally.
     if (!ReadOutputs(&block_scope, function, subst_output_validator,