content: make theme_color more resilient to casting issues

content/public/common/manifest.cc

Index: content/public/common/manifest.cc
diff --git a/content/public/common/manifest.cc b/content/public/common/manifest.cc
index ed19c470073b435008580c28e83da985666b65bb..53eae83a9b45cf618819b94ce366ac319c026b2a 100644
--- a/content/public/common/manifest.cc
+++ b/content/public/common/manifest.cc
@@ -7,7 +7,8 @@
 namespace content {
 
 const double Manifest::Icon::kDefaultDensity = 1;
-const int64_t Manifest::kInvalidOrMissingThemeColor = -1;
+const int64_t Manifest::kInvalidOrMissingThemeColor =
+    static_cast<int64_t>(std::numeric_limits<int32_t>::max()) + 1;

[Avi (use Gerrit), 2015/08/07 14:48:08]

I'm having trouble wrapping my brain around this.

I get that we don't have unsigned 32 bit integers in Java so we embed it in a
signed 64 bit one. But what is going on here? Can you clarify with a comment?

[Lalit Maganti, 2015/08/07 14:54:15]

Have added a comment in the new patch.

 const size_t Manifest::kMaxIPCStringLength = 4 * 1024;
 
 Manifest::Icon::Icon()