Allow .o files for GN generated inputs.

tools/gn/target.h

Index: tools/gn/target.h
diff --git a/tools/gn/target.h b/tools/gn/target.h
index eff4d150d53e5dd3a7856926c3ab0ed7d6925f3a..cbdab35761ef8e77c545921b5e958743b271951b 100644
--- a/tools/gn/target.h
+++ b/tools/gn/target.h
@@ -21,6 +21,7 @@
 #include "tools/gn/ordered_set.h"
 #include "tools/gn/output_file.h"
 #include "tools/gn/source_file.h"
+#include "tools/gn/toolchain.h"
 #include "tools/gn/unique_vector.h"
 
 class DepsIteratorRange;
@@ -66,6 +67,10 @@ class Target : public Item {
   OutputType output_type() const { return output_type_; }
   void set_output_type(OutputType t) { output_type_ = t; }
 
+  // True for targets that compile source code (all types of libaries and
+  // executables).
+  bool IsBinary() const;
+
   // Can be linked into other targets.
   bool IsLinkable() const;
 
@@ -245,6 +250,18 @@ class Target : public Item {
     return dependency_output_file_;
   }
 
+  // Computes the set of output files resulting from compiling the given source
+  // file. If the file can be compiled and the tool exists, fills the outputs
+  // in and writes the tool type to computed_tool_type. If the file is not
+  // compilable, returns false.
+  //
+  // The function can succeed with a "NONE" tool type for object files which
+  // are just passed to the output. The output will always be overwritten, not
+  // appended to.
+  bool GetOutputFilesForSource(const SourceFile& source,
+                               Toolchain::ToolType* computed_tool_type,
+                               std::vector<OutputFile>* outputs) const;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(Target, ResolvePrecompiledHeaders);