Add UMA stats to record when DLLs are successfully blocked in the Browser.

chrome_elf/blacklist/blacklist.h

Index: chrome_elf/blacklist/blacklist.h
diff --git a/chrome_elf/blacklist/blacklist.h b/chrome_elf/blacklist/blacklist.h
index 2e21f20793e296cfff766cd3728cf6238f9fe154..1530ae00dc917e5c2a14b83879733fa1b4ae6caa 100644
--- a/chrome_elf/blacklist/blacklist.h
+++ b/chrome_elf/blacklist/blacklist.h
@@ -12,7 +12,7 @@
 namespace blacklist {
 
 // Max size of the DLL blacklist.
-const int kTroublesomeDllsMaxCount = 64;
+const size_t kTroublesomeDllsMaxCount = 64;
 
 // The DLL blacklist.
 extern const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount];
@@ -68,12 +68,25 @@ extern "C" bool IsBlacklistInitialized();
 // the blacklist when this returns, false on error. Note that this will copy
 // |dll_name| and will leak it on exit if the string is not subsequently removed
 // using RemoveDllFromBlacklist.
+// Exposed for testing only, this shouldn't be exported from chrome_elf.dll.
 extern "C" bool AddDllToBlacklist(const wchar_t* dll_name);
 
 // Removes the given dll name from the blacklist. Returns true if it was
 // removed, false on error.
+// Exposed for testing only, this shouldn't be exported from chrome_elf.dll.
 extern "C" bool RemoveDllFromBlacklist(const wchar_t* dll_name);
 
+// Returns a list of all the dlls that have been successfully blocked by the
+// blacklist via blocked_dlls, if there is enough space (according to |size|).
+// |size| will always be modified to be the number of dlls that were blocked.
+// The caller doesn't own the strings and isn't expected to free them. These
+// strings won't be hanging unless RemoveDllFromBlacklist is called, but it
+// is only exposed in tests (and should stay that way).
+extern "C" void SuccessfullyBlocked(const wchar_t** blocked_dlls, int* size);

[sky, 2014/02/26 21:52:05]

Is there a reason this can't return std::vector<std::wstring> ? Seems like a
such a return type would be much more type safe.

[csharp, 2014/02/26 22:00:01]

This is usually called from across a dll boundary and I don't believe we can
easily or consistently pass c++ types.

+
+// Record that the dll at the given index was blocked.
+void BlockedDll(size_t blocked_index);
+
 // Initializes the DLL blacklist in the current process. This should be called
 // before any undesirable DLLs might be loaded. If |force| is set to true, then
 // initialization will take place even if a beacon is present. This is useful