Added new ReadFileToString API with a max_size argument

base/files/file_util_proxy_unittest.cc

Index: base/files/file_util_proxy_unittest.cc
diff --git a/base/files/file_util_proxy_unittest.cc b/base/files/file_util_proxy_unittest.cc
index 30c77d39884c3ce82004bc78e6a9871f62f08936..0e449884db24abf6d9c37cf17a134b8721348f52 100644
--- a/base/files/file_util_proxy_unittest.cc
+++ b/base/files/file_util_proxy_unittest.cc
@@ -217,6 +217,12 @@ TEST_F(FileUtilProxyTest, CreateTemporary) {
   EXPECT_TRUE(ReadFileToString(path_, &data));
   EXPECT_EQ("test", data);
 
+  EXPECT_FALSE(ReadFileToString(path_, &data, 0));

[Andrew T Wilson (Slow), 2014/02/10 14:29:46]

Can we move these to a separate test?

Also, can you add a test for ReadFileToString(path, NULL) which should return
true if there were no errors (since this functionality was broken in your CL)?

[kaliamoorthi, 2014/02/11 10:10:45]

Done.

+  EXPECT_FALSE(ReadFileToString(path_, &data, 2));

[bartfab (slow), 2014/02/10 14:55:37]

Nit: Could you order these tests by increasing maxsize? They appear a bit
chaotic right now.

[kaliamoorthi, 2014/02/11 10:10:45]

Done.

+  EXPECT_TRUE(ReadFileToString(path_, &data, 6));
+  EXPECT_FALSE(ReadFileToString(path_, &data, 3));
+  EXPECT_TRUE(ReadFileToString(path_, &data, 4));
+
   // Make sure we can & do delete the created file to prevent leaks on the bots.
   EXPECT_TRUE(base::DeleteFile(path_, false));
 }