Fix a leak in CJBig2_CachePair.

Fix a leak in CJBig2_CachePair.

R=jbreiden@google.com

Committed: https://pdfium.googlesource.com/pdfium/+/b6b336a0a1849526f66c49588daa2ccdd09d42cd

[Lei Zhang, 2015-09-18 02:47:52]

thestig@chromium.org changed reviewers:
+ jbreiden@google.com

[jbreiden, 2015-09-23 23:10:57]

lgtm

[Lei Zhang, 2015-09-23 23:50:57]

Committed patchset #1 (id:1) manually as
b6b336a0a1849526f66c49588daa2ccdd09d42cd (presubmit successful).

[jbreiden, 2015-09-24 00:08:36]

Saw this alternate implementation, just FYI.

while (!m_SymbolDictCache.empty()) {
    delete m_SymbolDictCache.back().second;
    m_SymbolDictCache.pop_back();
}

[Lei Zhang, 2015-09-24 05:51:07]

On 2015/09/24 00:08:36, jbreiden wrote:
> Saw this alternate implementation, just FYI.
> 
> while (!m_SymbolDictCache.empty()) {
>     delete m_SymbolDictCache.back().second;
>     m_SymbolDictCache.pop_back();
> }

Meh. No need to spend extra time to empty out m_SymbolDictCache.
CCodec_Jbig2Module owns m_SymbolDictCache and this is in ~CCodec_Jbig2Module.