Try to cut down Browser/TabContents header dependencies.

chrome/common/page_transition_types.cc

Index: chrome/common/page_transition_types.cc
diff --git a/chrome/common/page_transition_types.cc b/chrome/common/page_transition_types.cc
index 9fb49cd2d08812892c823c82ebcec37b35041efc..bf686f9abb150b24e504e4c7425823197272aab5 100644
--- a/chrome/common/page_transition_types.cc
+++ b/chrome/common/page_transition_types.cc
@@ -4,6 +4,20 @@
 
 #include "chrome/common/page_transition_types.h"
 
+#include "base/logging.h"
+
+// static
+PageTransition::Type PageTransition::FromInt(int32 type) {
+  if (!ValidType(type)) {
+    NOTREACHED() << "Invalid transition type " << type;
+
+    // Return a safe default so we don't have corrupt data in release mode.
+    return LINK;
+  }
+  return static_cast<Type>(type);
+}
+
+// static
 const char* PageTransition::CoreTransitionString(Type type) {
   switch (type & PageTransition::CORE_MASK) {
     case 0: return "link";