Places/Coding Style

As a general rule we follow conventions reported in the global coding style page: https://developer.mozilla.org/En/Developer_Guide/Coding_Style

With some differences:

if/else if/else conditions, as well as try/catch should never be inline with braces:

if (condition) {
  statement1;
  statement2;
}
else if (condition) {
  statement1;
  statement2;
}
else {
  statement1;
  statement2;
}

try {
  statement;
}
catch(ex) {}

Oneliners statements inside if/elseif/else conditions can avoid braces, but if any side of the condition uses braces then all sides will take them:

if (condition)
  statement;
else
  statement;

if (condition) {
  statement;
}
else {
  statement1;
  statement2;
}

When instantiating services in cpp use this form:

nsCOMPtr<nsIAnnotationService> annoSvc =
  do_GetService(NS_ANNOTATIONSERVICE_CONTRACTID);
NS_ENSURE_TRUE(annoSvc, NS_ERROR_OUT_OF_MEMORY);

To null check other pointers use NS_ENSURE_STATE(something);

When defining cpp methods opening brace and type are in new lines:

type*
newMethod(type param)
{
  impl;
}

Constructors params are inited like this (notice order of inited params should be the same as they are defined in the class definition, otherwise GCC will warn)

nsNavHistory::nsNavHistory()
: mBatchLevel(0)
, mBatchHasTransaction(PR_FALSE)
, mCachedNow(0)
, mExpireNowTimer(nsnull)
, mExpireDaysMin(0)
, mExpireDaysMax(0)
, mExpireSites(0)
, mNumVisitsForFrecency(10)
, mTagsFolder(-1)
, mInPrivateBrowsing(PRIVATEBROWSING_NOTINITED)
, mDatabaseStatus(DATABASE_STATUS_OK)
, mCanNotify(true)
, mCacheObservers("history-observers")
{
  impl;
}

Use namespace mozilla::places where possible, or anonymous namespace for file scope.

Add Places or nsPlaces in front of components or modules names, so that they are easily recognizeable in components/modules folders and also to prevent naming conflicts.

If both Coding style guide and this page cannot answer your question regarding code style, try checking Storage code style document, we don't follow all Storage code style conventions, but it contains some interesting idea.