Fix parsing of exponents in StringToDouble.

base/strings/string_number_conversions_unittest.cc

Index: base/strings/string_number_conversions_unittest.cc
diff --git a/base/strings/string_number_conversions_unittest.cc b/base/strings/string_number_conversions_unittest.cc
index 640468c33d5c6274c26b57affb26c95c5a46487a..a12cecfdfcda1101bd99c2876451f9a71558064c 100644
--- a/base/strings/string_number_conversions_unittest.cc
+++ b/base/strings/string_number_conversions_unittest.cc
@@ -728,7 +728,23 @@ TEST(StringNumberConversionsTest, StringToDouble) {
     {"2.99792458e8", 299792458.0, true},
     {"149597870.691E+3", 149597870691.0, true},
     {"6.", 6.0, true},
+    {"9e307", 9e307, true},
+    {"1.7976e308", 1.7976e308, true},

[danakj, 2016/09/01 23:49:23]

Can you drop a comment on all these new ones where these numbers come from/what
they are testing?

[Lei Zhang, 2016/09/02 01:07:10]

- Added comments for all the groups of cases.
- Added a few more test cases.

+    {"1.7977e308", HUGE_VAL, false},
+    {"9e308", HUGE_VAL, false},
+    {"9e309", HUGE_VAL, false},
+    {"9e999", HUGE_VAL, false},
+    {"9e1999", HUGE_VAL, false},
+    {"9e19999", HUGE_VAL, false},
     {"9e99999999999999999999", HUGE_VAL, false},
+    {"-9e307", -9e307, true},
+    {"-1.7976e308", -1.7976e308, true},
+    {"-1.7977e308", -HUGE_VAL, false},
+    {"-9e308", -HUGE_VAL, false},
+    {"-9e309", -HUGE_VAL, false},
+    {"-9e999", -HUGE_VAL, false},
+    {"-9e1999", -HUGE_VAL, false},
+    {"-9e19999", -HUGE_VAL, false},
     {"-9e99999999999999999999", -HUGE_VAL, false},
     {"1e-2", 0.01, true},
     {"42 ", 42.0, false},