Mark some flaky and failing tests as such.

chrome/test/ui/ppapi_uitest.cc

Index: chrome/test/ui/ppapi_uitest.cc
===================================================================
--- chrome/test/ui/ppapi_uitest.cc	(revision 55155)
+++ chrome/test/ui/ppapi_uitest.cc	(working copy)
@@ -91,7 +91,9 @@
   RunTest("DeviceContext2D");
 }
 
-TEST_F(PPAPITest, ImageData) {
+// TODO(brettw) bug 51344: this is flaky on bots. Seems to timeout navigating.
+// Possibly all the image allocations slow things down on a loaded bot too much.
+TEST_F(PPAPITest, FLAKY_ImageData) {
   RunTest("ImageData");
 }
 
@@ -99,7 +101,8 @@
   RunTest("Buffer");
 }
 
-TEST_F(PPAPITest, URLLoader) {
+// TODO(brettw) bug 51345: this failed consistently on one of the bots.
+TEST_F(PPAPITest, FAILS_URLLoader) {
   RunTestViaHTTP("URLLoader");
 }