Make pnacl install on demand when it is not already installed.

chrome/browser/component_updater/component_updater_service.cc

Index: chrome/browser/component_updater/component_updater_service.cc
diff --git a/chrome/browser/component_updater/component_updater_service.cc b/chrome/browser/component_updater/component_updater_service.cc
index f2d0155e2c6cd16dd34e57fa52d607dba6b3d2b6..8f7678a5246fb8e53b28ddf1fd3b1d4624676f5c 100644
--- a/chrome/browser/component_updater/component_updater_service.cc
+++ b/chrome/browser/component_updater/component_updater_service.cc
@@ -255,6 +255,8 @@ class CrxUpdateService : public ComponentUpdateService {
   virtual Status Stop() OVERRIDE;
   virtual Status RegisterComponent(const CrxComponent& component) OVERRIDE;
   virtual Status CheckForUpdateSoon(const CrxComponent& component) OVERRIDE;
+  virtual bool FindRegisteredComponent(const std::vector<uint8>& pk_hash,
+                                       CrxComponent* component) OVERRIDE;
 
   // The only purpose of this class is to forward the
   // UtilityProcessHostClient callbacks so CrxUpdateService does
@@ -499,6 +501,21 @@ ComponentUpdateService::Status CrxUpdateService::RegisterComponent(
   return kOk;
 }
 
+bool CrxUpdateService::FindRegisteredComponent(
+    const std::vector<uint8>& pk_hash,
+    CrxComponent* component) {
+  std::string id =
+      HexStringToID(StringToLowerASCII(base::HexEncode(&pk_hash[0],
+                                                       pk_hash.size()/2)));
+  CrxUpdateItem* uit = FindUpdateItemById(id);
+  if (uit) {
+    *component = uit->component;
+    return true;
+  }
+  return false;
+}
+
+
 // Sets a component to be checked for updates.
 // The componet to add is |crxit| and the |query| string is modified with the
 // required omaha compatible query. Returns false when the query strings