Populate stack frames with unloaded module info.

This CL hits lots of source files because:
 1. An update to the CodeModule virtual class. I added an is_loaded
  method to specify whether the module is loaded. There were several
  mocks/test classes that needed to be updated with an implementation.
  An alternative to this route would be to modify
  MinidumpUnloadedModule::code_file to prepend "Unloaded_" to the
  module name.

 2. Added an unloaded_modules parameter to
  StackFrameSymbolizer::FillSourceLineInfo.

BUG=

Change-Id: Ic9c7f7c7b7e932a154a5d4ccf292c1527d8da09f
Reviewed-on: https://chromium-review.googlesource.com/430241
Reviewed-by: Ivan Penkov <ivanpe@chromium.org>

src/processor/stackwalker_unittest_utils.h

@@ -118,6 +118,7 @@ class MockCodeModule: public google_breakpad::CodeModule {
   google_breakpad::CodeModule *Copy() const {
     abort(); // Tests won't use this.
   }
+  virtual bool is_unloaded() const { return false; }
   virtual uint64_t shrink_down_delta() const { return 0; }
   virtual void SetShrinkDownDelta(uint64_t shrink_down_delta) {}