Let x86 stackwalker scan stack in cases where program evaluation fails

src/processor/minidump_stackwalk.cc

Index: src/processor/minidump_stackwalk.cc
===================================================================
--- src/processor/minidump_stackwalk.cc	(revision 408)
+++ src/processor/minidump_stackwalk.cc	(working copy)
@@ -160,6 +160,28 @@
         sequence = PrintRegister("edx", frame_x86->context.edx, sequence);
         sequence = PrintRegister("efl", frame_x86->context.eflags, sequence);
       }
+      const char *trust_name;
+      switch (frame_x86->trust) {
+        case StackFrameX86::FRAME_TRUST_NONE:
+          trust_name = "unknown";
+          break;
+        case StackFrameX86::FRAME_TRUST_CONTEXT:
+	  trust_name = "given as instruction pointer in context";
+	  break;
+        case StackFrameX86::FRAME_TRUST_CFI:
+          trust_name = "call frame info";
+          break;
+        case StackFrameX86::FRAME_TRUST_CFI_SCAN:
+          trust_name = "call frame info with scanning";
+          break;
+        case StackFrameX86::FRAME_TRUST_FP:
+          trust_name = "previous frame's frame pointer";
+          break;
+        case StackFrameX86::FRAME_TRUST_SCAN:
+          trust_name = "stack scanning";
+          break;
+      }
+      printf("\n    Found by: %s", trust_name);
     } else if (cpu == "ppc") {
       const StackFramePPC *frame_ppc =
           reinterpret_cast<const StackFramePPC*>(frame);