Make WebSpellCheckClient aware of leak detection

chrome/renderer/spellchecker/spellcheck_provider.cc

Index: chrome/renderer/spellchecker/spellcheck_provider.cc
diff --git a/chrome/renderer/spellchecker/spellcheck_provider.cc b/chrome/renderer/spellchecker/spellcheck_provider.cc
index 53b30a9584f392be8d85377d1a85b8d619030859..c544478e92a4f2ec18d59c34cd65999095ce6953 100644
--- a/chrome/renderer/spellchecker/spellcheck_provider.cc
+++ b/chrome/renderer/spellchecker/spellcheck_provider.cc
@@ -175,6 +175,13 @@ void SpellCheckProvider::requestCheckingOfText(
   UMA_HISTOGRAM_COUNTS("SpellCheck.api.async", text.length());
 }
 
+void SpellCheckProvider::prepareForLeakDetection() {

[please use gerrit instead, 2016/08/09 16:47:57]

Let's use a name that better describes what happens in this function. For
example, "cancelCheckingAllText". What do you think?

[Xiaocheng, 2016/08/10 01:14:47]

Renamed to "cancelAllPendingRequests", which sounds better to me.

+  for (WebTextCheckCompletions::iterator iter(&text_check_completions_);
+       !iter.IsAtEnd(); iter.Advance())
+    iter.GetCurrentValue()->didCancelCheckingText();
+  text_check_completions_.Clear();
+}
+
 void SpellCheckProvider::showSpellingUI(bool show) {
 #if defined(USE_BROWSER_SPELLCHECKER)
   UMA_HISTOGRAM_BOOLEAN("SpellCheck.api.showUI", show);