Add shared bitmap managers for browser and renderer processes.

cc/resources/shared_bitmap.cc

Index: cc/resources/shared_bitmap.cc
diff --git a/cc/resources/shared_bitmap.cc b/cc/resources/shared_bitmap.cc
index 3a6fc3589e3a8471b9a4d10e75278c76bfbe0a41..3caab4050d13d26e630c52af16cdf86013a9e516 100644
--- a/cc/resources/shared_bitmap.cc
+++ b/cc/resources/shared_bitmap.cc
@@ -4,6 +4,8 @@
 
 #include "cc/resources/shared_bitmap.h"
 
+#include "base/rand_util.h"
+
 namespace cc {
 
 SharedBitmap::SharedBitmap(
@@ -14,4 +16,28 @@ SharedBitmap::SharedBitmap(
 
 SharedBitmap::~SharedBitmap() { free_callback_.Run(this); }
 
+// static
+bool SharedBitmap::GetSizeInBytes(const gfx::Size& size,
+                                  size_t* size_in_bytes) {
+  static const size_t kMaxSize = static_cast<size_t>(INT_MAX);
+  const size_t stride = 4 * size.width();
+  if (size.width() <= 0 || size.height() <= 0 ||
+      static_cast<size_t>(size.width()) > (kMaxSize / 4) ||
+      static_cast<size_t>(size.height()) > (kMaxSize / stride)) {
+    return false;
+  }
+
+  *size_in_bytes = size.GetArea() * 4;

[jschuh, 2014/03/08 00:58:11]

I think the base::CheckedNumeric template would make the math and overflow
checks clearer.

+
+  return true;
+}
+
+// static
+SharedBitmapId SharedBitmap::GenerateId() {
+  SharedBitmapId id;
+  // Needs cryptographically-secure random numbers.
+  base::RandBytes(id.name, sizeof(id.name));
+  return id;
+}
+
 }  // namespace cc