Code:  PepperDeviceEnumerationHostHelper::PepperDeviceEnumerationHostHelper(
     ppapi::host::ResourceHost* resource_host,
    Delegate* delegate,
     PP_DeviceType_Dev device_type,
     const GURL& document_url)
     : resource_host_(resource_host),
      delegate_(delegate),
      device_type_(device_type),
      document_url_(document_url) {}

Vulnerability Type: DoS 
CWE ID: CWE-399
Summary: Use-after-free vulnerability in the Pepper plugins in Google Chrome before 39.0.2171.65 allows remote attackers to cause a denial of service or possibly have unspecified other impact via crafted Flash content that triggers an attempted PepperMediaDeviceManager access outside of the object's lifetime.
Commit Message: Pepper: Access PepperMediaDeviceManager through a WeakPtr

Its lifetime is scoped to the RenderFrame, and it might go away before the
hosts that refer to it.

BUG=423030

Review URL: https://codereview.chromium.org/653243003

Cr-Commit-Position: refs/heads/master@{#299897}