Revert 257161 "Revert 256955 "Add shared bitmap managers for bro..."

Turns out the child process was mapping the memory twice, so fixed that.

> Revert 256955 "Add shared bitmap managers for browser and render..."
> 
> Seems to be causing renderer crashes and possibly out-of-memory issues.
> 
> > Add shared bitmap managers for browser and renderer processes.
> > 
> > The shared bitmap managers will allow software tiles to be allocated in shared memory, so delegated rendering could be used with them.
> > 
> > BUG=327220
> > R=danakj@chromium.org, jschuh@chromium.org, piman@chromium.org
> > 
> > Review URL: https://codereview.chromium.org/148243013
> 
> TBR=jbauman@chromium.org
> 
> Review URL: https://codereview.chromium.org/197703004

TBR=jbauman@chromium.org

Review URL: https://codereview.chromium.org/200913002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257216 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 25 insertions, 0 deletions

diff --git a/cc/resources/shared_bitmap.cc b/cc/resources/shared_bitmap.cc
index 3a6fc35..3b94d45 100644
--- a/cc/resources/shared_bitmap.cc
+++ b/cc/resources/shared_bitmap.cc
@@ -4,6 +4,9 @@
 
 #include "cc/resources/shared_bitmap.h"
 
+#include "base/numerics/safe_math.h"
+#include "base/rand_util.h"
+
 namespace cc {
 
 SharedBitmap::SharedBitmap(
@@ -14,4 +17,26 @@ SharedBitmap::SharedBitmap(
 
 SharedBitmap::~SharedBitmap() { free_callback_.Run(this); }
 
+// static
+bool SharedBitmap::GetSizeInBytes(const gfx::Size& size,
+                                  size_t* size_in_bytes) {
+  if (size.width() <= 0 || size.height() <= 0)
+    return false;
+  base::CheckedNumeric<int> s = size.width();
+  s *= size.height();
+  s *= 4;
+  if (!s.IsValid())
+    return false;
+  *size_in_bytes = s.ValueOrDie();
+  return true;
+}
+
+// static
+SharedBitmapId SharedBitmap::GenerateId() {
+  SharedBitmapId id;
+  // Needs cryptographically-secure random numbers.
+  base::RandBytes(id.name, sizeof(id.name));
+  return id;
+}
+
 }  // namespace cc