Make it possible to enable/disable specific ppapi tests. Migrate PostMessage tests.

ppapi/tests/testing_instance.h

Index: ppapi/tests/testing_instance.h
diff --git a/ppapi/tests/testing_instance.h b/ppapi/tests/testing_instance.h
index 0c79923dbf83840cc5d973d812d5249b655d6ab8..4548e26480c91df8b6be7c679a22a8a3a623f6a1 100644
--- a/ppapi/tests/testing_instance.h
+++ b/ppapi/tests/testing_instance.h
@@ -87,8 +87,11 @@ pp::InstancePrivate {
   void ExecuteTests(int32_t unused);
 
   // Creates a new TestCase for the give test name, or NULL if there is no such
-  // test. Ownership is passed to the caller.
-  TestCase* CaseForTestName(const char* name);
+  // test. Ownership is passed to the caller. The given string is split by '_'.
+  // The test case name is the first part.
+  TestCase* CaseForTestName(const std::string& name);
+  // Returns the filter (second part) of the given string.
+  std::string FilterForTestName(const std::string& name);
 
   // Appends a list of available tests to the console in the document.
   void LogAvailableTests();
@@ -109,6 +112,10 @@ pp::InstancePrivate {
   // Owning pointer to the current test case. Valid after Init has been called.
   TestCase* current_case_;
 
+  // A filter to use when running tests. This is passed to 'RunTests', which
+  // runs only tests whose name contains test_filter_ as a substring.
+  std::string test_filter_;
+
   // The current step we're on starting at 0. This is incremented every time we
   // report progress via a cookie. See comment above the class.
   int progress_cookie_number_;