[GN] Export include directories, defines and dialects to Xcode projects

tools/gn/xcode_object.h

Index: tools/gn/xcode_object.h
diff --git a/tools/gn/xcode_object.h b/tools/gn/xcode_object.h
index 2ad43cceefc4567abad8d2ca2123794f0c0cf606..2c1771daa53f9968d418f3bcd4d102650d2eb4ed 100644
--- a/tools/gn/xcode_object.h
+++ b/tools/gn/xcode_object.h
@@ -58,7 +58,7 @@ class PBXTarget;
 class XCBuildConfiguration;
 class XCConfigurationList;
 
-using PBXAttributes = std::map<std::string, std::string>;
+using PBXAttributes = std::multimap<std::string, std::string>;
 
 // PBXObjectVisitor -----------------------------------------------------------
 
@@ -154,7 +154,8 @@ class PBXAggregateTarget : public PBXTarget {
 class PBXBuildFile : public PBXObject {
  public:
   PBXBuildFile(const PBXFileReference* file_reference,
-               const PBXSourcesBuildPhase* build_phase);
+               const PBXSourcesBuildPhase* build_phase,
+               const std::string& cflags);
   ~PBXBuildFile() override;
 
   // PXBObject implementation.
@@ -165,6 +166,7 @@ class PBXBuildFile : public PBXObject {
  private:
   const PBXFileReference* file_reference_;
   const PBXSourcesBuildPhase* build_phase_;
+  std::string cflags_;
 
   DISALLOW_COPY_AND_ASSIGN(PBXBuildFile);
 };
@@ -247,7 +249,8 @@ class PBXNativeTarget : public PBXTarget {
                   const PBXFileReference* product_reference);
   ~PBXNativeTarget() override;
 
-  void AddFileForIndexing(const PBXFileReference* file_reference);
+  void AddFileForIndexing(const PBXFileReference* file_reference,
+                          const std::string& cflags);
 
   // PBXObject implementation.
   PBXObjectClass Class() const override;
@@ -271,7 +274,9 @@ class PBXProject : public PBXObject {
              const PBXAttributes& attributes);
   ~PBXProject() override;
 
-  void AddSourceFile(const std::string& source_path);
+  static bool SourceFileShouldBeIndexed(const std::string& sourcePath);
+
+  void AddSourceFile(const std::string& source_path, const std::string& cflags);
   void AddAggregateTarget(const std::string& name,
                           const std::string& shell_script);
   void AddNativeTarget(const std::string& name,