Tracing V2: Import support for protobuf plugin.

components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc

Index: components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
diff --git a/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc b/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
index 12a32ab3783581e3665d5da37145670dc847255d..fd034b6285609834dc8b7c79c8e8bb29ae051094 100644
--- a/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
+++ b/components/tracing/tools/proto_zero_plugin/proto_zero_generator.cc
@@ -33,6 +33,10 @@ using google::protobuf::UpperString;
 
 namespace {
 
+inline std::string ProtoStubName(const FileDescriptor* proto) {
+  return StripSuffixString(proto->name(), ".proto") + ".pbzero";
+}
+
 class GeneratorJob {
  public:
   GeneratorJob(const FileDescriptor *file,
@@ -151,7 +155,7 @@ class GeneratorJob {
         "#define $guard$\n\n"
         "#include <stddef.h>\n"
         "#include <stdint.h>\n\n"
-        "#include \"components/tracing/core/proto_zero_message.h\"\n\n",
+        "#include \"components/tracing/core/proto_zero_message.h\"\n",
         "greeting", greeting,
         "guard", guard);
     stub_cc_->Print(
@@ -159,6 +163,29 @@ class GeneratorJob {
         "// This file intentionally left blank.\n",
         "greeting", greeting);
 
+    // Print dependencies.
+    if (source_->weak_dependency_count() > 0)
+      Abort("Weak imports are not supported.");
+    for (int i = 0; i < source_->dependency_count(); ++i) {
+      const FileDescriptor* dependency = source_->dependency(i);
+      if (dependency->package() != package_)
+        Abort("Imported proto must be in the same package.");

[Primiano Tucci (use gerrit), 2016/08/03 15:36:28]

out of curiosity, why?

[kraynov, 2016/08/04 12:03:54]

It would be complex to deal with namespaces in this case.

+
+      // Dependency name could contatin slashes but importing from upper-level
+      // directories is not possible anyway since build system process each
+      // proto file individually. Hence proto lookup path always equal to the
+      // directory where particular proto file is located and protoc does not
+      // allow reference to upper directory (aka ..) in import path.
+      //
+      // Laconiacally said:

[Primiano Tucci (use gerrit), 2016/08/03 15:36:28]

nit: s/Laconiacally/Laconically/

+      // - source_->name() may never have slashes,
+      // - dependency->name() may have slashes but always reffers to inner path.
+      stub_h_->Print(
+          "#include \"$name$.h\"\n",
+          "name", ProtoStubName(dependency));
+    }
+    stub_h_->Print("\n");
+
     // Print namespaces.
     for (const std::string& ns : namespaces_)
       stub_h_->Print("namespace $ns$ {\n", "ns", ns);
@@ -402,13 +429,10 @@ bool ProtoZeroGenerator::Generate(const FileDescriptor* file,
                                   GeneratorContext* context,
                                   std::string* error) const {
 
-  const std::string proto_stubs_name =
-      StripSuffixString(file->name(), ".proto") + ".pbzero";
-
   const std::unique_ptr<ZeroCopyOutputStream> stub_h_file_stream(
-      context->Open(proto_stubs_name + ".h"));
+      context->Open(ProtoStubName(file) + ".h"));
   const std::unique_ptr<ZeroCopyOutputStream> stub_cc_file_stream(
-      context->Open(proto_stubs_name + ".cc"));
+      context->Open(ProtoStubName(file) + ".cc"));
 
   // Variables are delimited by $.
   Printer stub_h_printer(stub_h_file_stream.get(), '$');