Print the symbol displacement in the stack traces printed by agent_logger.

Here's how the stack traces currently look like:
    #0 0x0000540fd6ee in base::debug::AsanHeapOverflow c:\b\build\slave\win-asan\build\src\base\debug\asan_invalid_access.cc:64
    #1 0x000054b88806 in content::`anonymous namespace'::HandleAsanDebugURL c:\b\build\slave\win-asan\build\src\content\browser\frame_host\debug_urls.cc:98
    #2 0x000054b888aa in content::HandleDebugURL c:\b\build\slave\win-asan\build\src\content\browser\frame_host\debug_urls.cc:126
    #3 0x000054b5313d in content::NavigationControllerImpl::LoadURLWithParams c:\b\build\slave\win-asan\build\src\content\browser\frame_host\navigation_controller_impl.cc:655
    #4 0x0000549f50af in `anonymous namespace'::LoadURLInContents c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_navigator.cc:285
    #5 0x0000549f57a3 in chrome::Navigate c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_navigator.cc:637
    #6 0x000054a04312 in chrome::OpenCurrentURL c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_commands.cc:541
    #7 0x0000549ff88b in chrome::BrowserCommandController::ExecuteCommandWithDisposition c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_command_controller.cc:396
    #8 0x00005510db62 in CommandUpdater::ExecuteCommandWithDisposition c:\b\build\slave\win-asan\build\src\chrome\browser\command_updater.cc:51
    #9 0x00005510daf5 in CommandUpdater::ExecuteCommand c:\b\build\slave\win-asan\build\src\chrome\browser\command_updater.cc:44
    #10 0x00005571448e in OmniboxEditController::OnAutocompleteAccept c:\b\build\slave\win-asan\build\src\chrome\browser\ui\omnibox\omnibox_edit_controller.cc:20

And now with this patch:
    #0 0x000056cfd6ee in base::debug::AsanHeapOverflow+29 c:\b\build\slave\win-asan\build\src\base\debug\asan_invalid_access.cc:64
    #1 0x000057788806 in content::`anonymous namespace'::HandleAsanDebugURL+246 c:\b\build\slave\win-asan\build\src\content\browser\frame_host\debug_urls.cc:98
    #2 0x0000577888aa in content::HandleDebugURL+124 c:\b\build\slave\win-asan\build\src\content\browser\frame_host\debug_urls.cc:126
    #3 0x00005775313d in content::NavigationControllerImpl::LoadURLWithParams+127 c:\b\build\slave\win-asan\build\src\content\browser\frame_host\navigation_controller_impl.cc:655
    #4 0x0000575f50af in `anonymous namespace'::LoadURLInContents+310 c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_navigator.cc:285
    #5 0x0000575f57a3 in chrome::Navigate+767 c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_navigator.cc:637
    #6 0x000057604312 in chrome::OpenCurrentURL+202 c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_commands.cc:541
    #7 0x0000575ff88b in chrome::BrowserCommandController::ExecuteCommandWithDisposition+164 c:\b\build\slave\win-asan\build\src\chrome\browser\ui\browser_command_controller.cc:396
    #8 0x000057d0db62 in CommandUpdater::ExecuteCommandWithDisposition+44 c:\b\build\slave\win-asan\build\src\chrome\browser\command_updater.cc:51
    #9 0x000057d0daf5 in CommandUpdater::ExecuteCommand+13 c:\b\build\slave\win-asan\build\src\chrome\browser\command_updater.cc:44
    #10 0x00005831448e in OmniboxEditController::OnAutocompleteAccept+56 c:\b\build\slave\win-asan\build\src\chrome\browser\ui\omnibox\omnibox_edit_controller.cc:20

R=chrisha@chromium.org

BUG=

Review URL: https://codereview.appspot.com/145610044