[PPAPI] ResourceVar now reference counts its Resource in the plugin.

ResourceVar is now an abstract base class with subclasses
HostResourceVar and PluginResourceVar. The PluginResourceVar has a
reference counted Resource instead of a PP_Resource.

VarTracker has MakeResourceVar and MakeResourcePPVar methods, to
abstract over the creation of a resource var of the correct subclass.

Also, the creation_message is now NULL when empty, instead of being an
empty message object.

BUG=290713

Review URL: https://chromiumcodereview.appspot.com/23809016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224717 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 64 insertions, 58 deletions

diff --git a/ppapi/shared_impl/resource_var.cc b/ppapi/shared_impl/resource_var.cc
index c5719aa..3e34c38 100644
--- a/ppapi/shared_impl/resource_var.cc
+++ b/ppapi/shared_impl/resource_var.cc
@@ -9,18 +9,8 @@
 
 namespace ppapi {
 
-ResourceVar::ResourceVar() : pp_resource_(0) {}
-
-ResourceVar::ResourceVar(PP_Resource pp_resource) : pp_resource_(pp_resource) {}
-
-ResourceVar::ResourceVar(const IPC::Message& creation_message)
-    : pp_resource_(0),
-      creation_message_(creation_message) {}
-
-ResourceVar::~ResourceVar() {}
-
-bool ResourceVar::IsPending() const {
-  return pp_resource_ == 0 && creation_message_.type() != 0;
+const IPC::Message* ResourceVar::GetCreationMessage() const {
+  return NULL;
 }
 
 ResourceVar* ResourceVar::AsResourceVar() {
@@ -42,4 +32,8 @@ ResourceVar* ResourceVar::FromPPVar(PP_Var var) {
   return var_object->AsResourceVar();
 }
 
+ResourceVar::ResourceVar() {}
+
+ResourceVar::~ResourceVar() {}
+
 }  // namespace ppapi
diff --git a/ppapi/shared_impl/resource_var.h b/ppapi/shared_impl/resource_var.h
index 70eabc6..0b8bab2 100644
--- a/ppapi/shared_impl/resource_var.h
+++ b/ppapi/shared_impl/resource_var.h
@@ -5,42 +5,34 @@
 #ifndef PPAPI_SHARED_IMPL_RESOURCE_VAR_H_
 #define PPAPI_SHARED_IMPL_RESOURCE_VAR_H_
 
-#include "ipc/ipc_message.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 #include "ppapi/shared_impl/var.h"
 
+namespace IPC {
+class Message;
+}
+
 namespace ppapi {
 
 // Represents a resource Var.
 class PPAPI_SHARED_EXPORT ResourceVar : public Var {
  public:
-  // Makes a null resource var.
-  ResourceVar();
-
-  // Makes a resource var with an existing plugin-side resource.
-  explicit ResourceVar(PP_Resource pp_resource);
-
-  // Makes a resource var with a pending resource host.
-  // The |creation_message| contains instructions on how to create the
-  // plugin-side resource. Its type depends on the type of resource.
-  explicit ResourceVar(const IPC::Message& creation_message);
-
-  virtual ~ResourceVar();
-
   // Gets the resource ID associated with this var.
-  // This is 0 if a resource is still pending.
-  PP_Resource pp_resource() const { return pp_resource_; }
+  // This is 0 if a resource is still pending (only possible on the host side).
+  // NOTE: This can return a PP_Resource with a reference count of 0 on the
+  // plugin side. It should be AddRef'd if the resource is passed to the user.
+  virtual PP_Resource GetPPResource() const = 0;
 
-  // Gets the message for creating a plugin-side resource.
-  // May be an empty message.
-  const IPC::Message& creation_message() const { return creation_message_; }
+  // Gets the message for creating a plugin-side resource. Returns NULL if the
+  // message is empty (which is always true on the plugin side).
+  virtual const IPC::Message* GetCreationMessage() const;
 
   // Determines whether this is a pending resource.
-  // This is true if the pp_resource is 0 and there is a non-empty
-  // creation_message.
-  bool IsPending() const;
+  // This is true if, on the host side, the there is a creation_message and no
+  // PP_Resource.
+  virtual bool IsPending() const = 0;
 
   // Var override.
   virtual ResourceVar* AsResourceVar() OVERRIDE;
@@ -50,16 +42,12 @@ class PPAPI_SHARED_EXPORT ResourceVar : public Var {
   // return NULL if the PP_Var is not of Resource type.
   static ResourceVar* FromPPVar(PP_Var var);
 
- private:
-  // Real resource ID in the plugin. 0 if one has not yet been created
-  // (indicating that there is a pending host resource).
-  PP_Resource pp_resource_;
+ protected:
+  ResourceVar();
 
-  // If the plugin-side resource has not yet been created, carries a message to
-  // create a resource of the specific type on the plugin side.
-  // Otherwise, carries an empty message.
-  IPC::Message creation_message_;
+  virtual ~ResourceVar();
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ResourceVar);
 };
 
diff --git a/ppapi/shared_impl/test_globals.h b/ppapi/shared_impl/test_globals.h
index 709438e..2a0ece3 100644
--- a/ppapi/shared_impl/test_globals.h
+++ b/ppapi/shared_impl/test_globals.h
@@ -18,6 +18,9 @@ class TestVarTracker : public VarTracker {
  public:
   TestVarTracker() : VarTracker(THREAD_SAFE) {}
   virtual ~TestVarTracker() {}
+  virtual ResourceVar* MakeResourceVar(PP_Resource pp_resource) OVERRIDE {
+    return NULL;
+  }
   virtual ArrayBufferVar* CreateArrayBuffer(uint32 size_in_bytes) OVERRIDE {
     return NULL;
   }
diff --git a/ppapi/shared_impl/unittest_utils.cc b/ppapi/shared_impl/unittest_utils.cc
index f613882..6974bd2 100644
--- a/ppapi/shared_impl/unittest_utils.cc
+++ b/ppapi/shared_impl/unittest_utils.cc
@@ -8,6 +8,7 @@
 
 #include "base/containers/hash_tables.h"
 #include "base/logging.h"
+#include "ipc/ipc_message.h"
 #include "ppapi/shared_impl/array_var.h"
 #include "ppapi/shared_impl/dictionary_var.h"
 #include "ppapi/shared_impl/resource_var.h"
@@ -156,17 +157,19 @@ bool Equals(const PP_Var& expected,
       ResourceVar* expected_var = ResourceVar::FromPPVar(expected);
       ResourceVar* actual_var = ResourceVar::FromPPVar(actual);
       DCHECK(expected_var && actual_var);
-      if (expected_var->pp_resource() != actual_var->pp_resource()) {
-        LOG(ERROR) << "expected: " << expected_var->pp_resource() << " actual: "
-                   << actual_var->pp_resource();
+      if (expected_var->GetPPResource() != actual_var->GetPPResource()) {
+        LOG(ERROR) << "expected: " << expected_var->GetPPResource()
+                   << " actual: " << actual_var->GetPPResource();
         return false;
       }
-      IPC::Message actual_message(actual_var->creation_message());
-      const IPC::Message& expected_message = expected_var->creation_message();
-      if (expected_message.size() != actual_message.size()) {
+
+      const IPC::Message* actual_message = actual_var->GetCreationMessage();
+      const IPC::Message* expected_message =
+          expected_var->GetCreationMessage();
+      if (expected_message->size() != actual_message->size()) {
         LOG(ERROR) << "expected creation message size: "
-                   << expected_message.size() << " actual: "
-                   << actual_message.size();
+                   << expected_message->size() << " actual: "
+                   << actual_message->size();
         return false;
       }
 
@@ -174,12 +177,13 @@ bool Equals(const PP_Var& expected,
       // expected. This is an unpredictable reference number that changes
       // between serialization/deserialization, and we do not want it to cause
       // the comparison to fail.
-      actual_message.SetHeaderValues(actual_message.routing_id(),
-                                     actual_message.type(),
-                                     (expected_message.flags() & 0xffffff00) |
-                                      (actual_message.flags() & 0xff));
-      if (memcmp(expected_message.data(), actual_message.data(),
-                 expected_message.size()) != 0) {
+      IPC::Message local_actual_message(*actual_message);
+      local_actual_message.SetHeaderValues(
+          actual_message->routing_id(), actual_message->type(),
+          (expected_message->flags() & 0xffffff00) |
+           (actual_message->flags() & 0xff));
+      if (memcmp(expected_message->data(), local_actual_message.data(),
+                 expected_message->size()) != 0) {
         LOG(ERROR) << "expected creation message does not match actual.";
         return false;
       }
diff --git a/ppapi/shared_impl/var.cc b/ppapi/shared_impl/var.cc
index 9644a44..d128d90 100644
--- a/ppapi/shared_impl/var.cc
+++ b/ppapi/shared_impl/var.cc
@@ -71,8 +71,8 @@ std::string Var::PPVarToLogString(PP_Var var) {
 
       if (resource->IsPending()) {
         return base::StringPrintf("[Pending resource]");
-      } else if (resource->pp_resource()) {
-        return base::StringPrintf("[Resource %d]", resource->pp_resource());
+      } else if (resource->GetPPResource()) {
+        return base::StringPrintf("[Resource %d]", resource->GetPPResource());
       } else {
         return "[Null resource]";
       }
diff --git a/ppapi/shared_impl/var_tracker.cc b/ppapi/shared_impl/var_tracker.cc
index 254c51a..bada0ab 100644
--- a/ppapi/shared_impl/var_tracker.cc
+++ b/ppapi/shared_impl/var_tracker.cc
@@ -13,6 +13,7 @@
 #include "ppapi/shared_impl/host_resource.h"
 #include "ppapi/shared_impl/id_assignment.h"
 #include "ppapi/shared_impl/proxy_lock.h"
+#include "ppapi/shared_impl/resource_var.h"
 #include "ppapi/shared_impl/var.h"
 
 namespace ppapi {
@@ -234,6 +235,13 @@ PP_Var VarTracker::MakeArrayBufferPPVar(uint32 size_in_bytes,
   return array_buffer->GetPPVar();
 }
 
+PP_Var VarTracker::MakeResourcePPVar(PP_Resource pp_resource) {
+  CheckThreadingPreconditions();
+
+  ResourceVar* resource_var = MakeResourceVar(pp_resource);
+  return resource_var ? resource_var->GetPPVar() : PP_MakeNull();
+}
+
 std::vector<PP_Var> VarTracker::GetLiveVars() {
   CheckThreadingPreconditions();
 
diff --git a/ppapi/shared_impl/var_tracker.h b/ppapi/shared_impl/var_tracker.h
index d7fb49c..379f645 100644
--- a/ppapi/shared_impl/var_tracker.h
+++ b/ppapi/shared_impl/var_tracker.h
@@ -85,6 +85,15 @@ class PPAPI_SHARED_EXPORT VarTracker {
   // usually immediately put this in a scoped_refptr).
   ArrayBufferVar* MakeArrayBufferVar(uint32 size_in_bytes, const void* data);
 
+  // Creates a new resource var that points to a given resource ID. Returns a
+  // PP_Var that references it and has an initial reference count of 1.
+  PP_Var MakeResourcePPVar(PP_Resource pp_resource);
+
+  // Creates a new resource var that points to a given resource ID. This is
+  // implemented by the host and plugin tracker separately, because the plugin
+  // keeps a reference to the resource, and the host does not.
+  virtual ResourceVar* MakeResourceVar(PP_Resource pp_resource) = 0;
+
   // Return a vector containing all PP_Vars that are in the tracker. This is
   // to help implement PPB_Testing_Dev.GetLiveVars and should generally not be
   // used in production code. The PP_Vars are returned in no particular order,