Use PASS() everywhere in ppapi/tests.

ppapi/tests/test_graphics_2d.cc

Index: ppapi/tests/test_graphics_2d.cc
diff --git a/ppapi/tests/test_graphics_2d.cc b/ppapi/tests/test_graphics_2d.cc
index 1ba8f7f8fd7fb8406d469bebb666d577e9dcbee6..c9d6a9e7c02769079e9826e41800ef403812078d 100644
--- a/ppapi/tests/test_graphics_2d.cc
+++ b/ppapi/tests/test_graphics_2d.cc
@@ -233,7 +233,7 @@ std::string TestGraphics2D::TestInvalidResource() {
                                         &zero_zero))
     return "ReadImageData succeeded with a NULL resource";
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestInvalidSize() {
@@ -257,14 +257,14 @@ std::string TestGraphics2D::TestInvalidSize() {
   ASSERT_FALSE(!!graphics_2d_interface_->Create(
       pp::Module::Get()->pp_module(), &size, PP_FALSE));
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestHumongous() {
   pp::Graphics2D a(pp::Size(100000, 100000), false);
   if (!a.is_null())
     return "Humongous device created";
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestInitToZero() {
@@ -286,7 +286,7 @@ std::string TestGraphics2D::TestInitToZero() {
   if (!IsSquareInImage(image, 0, pp::Rect(0, 0, w, h), 0))
     return "Got a nonzero pixel";
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestDescribe() {
@@ -305,7 +305,7 @@ std::string TestGraphics2D::TestDescribe() {
   if (size.width != w || size.height != h || is_always_opaque != PP_FALSE)
     return "Mismatch of data.";
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestPaint() {
@@ -383,7 +383,7 @@ std::string TestGraphics2D::TestPaint() {
                     subset_color))
     return "Subset paint failed.";
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestScroll() {
@@ -445,7 +445,7 @@ std::string TestGraphics2D::TestScroll() {
   if (!CompareImages(test_image, readback))
     return "TC2, Read back image is not the same as test image.";
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestReplace() {
@@ -498,7 +498,7 @@ std::string TestGraphics2D::TestReplace() {
   if (!IsDCUniformColor(dc, swapped_color))
     return "Flushed color incorrect (or failure in readback).";
 
-  return "";
+  PASS();
 }
 
 std::string TestGraphics2D::TestFlush() {
@@ -540,5 +540,5 @@ std::string TestGraphics2D::TestFlush() {
       return "Second flush succeeded before callback ran.";
   }
 
-  return "";
+  PASS();
 }