[chromedriver] Add an error autoreporting feature that automatically raises errors from browser logs

chrome/test/chromedriver/logging.h

Index: chrome/test/chromedriver/logging.h
diff --git a/chrome/test/chromedriver/logging.h b/chrome/test/chromedriver/logging.h
index 505ede8357a1709b7f7498b4f107540db9a0c4f2..eb2cde881ca6ac460cbb1232792848ea086b1f41 100644
--- a/chrome/test/chromedriver/logging.h
+++ b/chrome/test/chromedriver/logging.h
@@ -39,6 +39,10 @@ class WebDriverLog : public Log {
   // creates and owns a new empty ListValue for further accumulation.
   scoped_ptr<base::ListValue> GetAndClearEntries();
 
+  // Finds the first error message in the log and returns it. If none exist,

[chrisgao (Use stgao instead), 2014/01/09 22:11:55]

nit: exist -> exists ?

[samuong, 2014/01/16 00:29:28]

I think it's "if none exist" or "if nothing exists", but not "if none exists".
Frank, let me know if I'm wrong.

+  // returns an empty string. Does not clear entries.
+  std::string GetFirstErrorMessage() const;

[chrisgao (Use stgao instead), 2014/01/09 22:11:55]

What's the consideration behind only returning the first error message, not all
available error messages?

[samuong, 2014/01/16 00:29:28]

The first error message gets returned to the client, and gets used as the
exception message. I don't think it's necessary to return all error messages,
but if the client is interested it can always call the GET_LOG command.

+
   // Translates a Log entry level into a WebDriver level and stores the entry.
   virtual void AddEntryTimestamped(const base::Time& timestamp,
                                    Level level,