Generate Instance ID locally.

components/gcm_driver/instance_id/instance_id_impl.cc

Index: components/gcm_driver/instance_id/instance_id_impl.cc
diff --git a/components/gcm_driver/instance_id/instance_id_impl.cc b/components/gcm_driver/instance_id/instance_id_impl.cc
index 4d76ad2286cde3fddb590f048170526d1b93b50c..1dfaab78ec9e5a95f1fd39eb076436f1ba1d6ca7 100644
--- a/components/gcm_driver/instance_id/instance_id_impl.cc
+++ b/components/gcm_driver/instance_id/instance_id_impl.cc
@@ -4,7 +4,12 @@
 
 #include "components/gcm_driver/instance_id/instance_id_impl.h"
 
+#include <algorithm>
+#include "base/base64.h"
+#include "base/bind.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "crypto/random.h"
 
 namespace instance_id {
 
@@ -21,13 +26,12 @@ InstanceIDImpl::~InstanceIDImpl() {
 }
 
 std::string InstanceIDImpl::GetID() {
-  NOTIMPLEMENTED();
-  return std::string();
+  EnsureIDGenerated();
+  return id_;
 }
 
 base::Time InstanceIDImpl::GetCreationTime() {
-  NOTIMPLEMENTED();
-  return base::Time();
+  return creation_time_;
 }
 
 void InstanceIDImpl::GetToken(
@@ -45,7 +49,45 @@ void InstanceIDImpl::DeleteToken(const std::string& audience,
 }
 
 void InstanceIDImpl::DeleteID(const DeleteIDCallback& callback) {
-  NOTIMPLEMENTED();
+  // TODO(jianli): Delete the ID from the store.
+  id_.clear();
+  creation_time_ = base::Time();
+
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(callback, this, InstanceID::SUCCESS));
+}
+
+void InstanceIDImpl::EnsureIDGenerated() {
+  if (!id_.empty())
+    return;
+
+  // Now produce the ID in the following steps:
+
+  // 1) Generates the random number in 8 bytes which is required by the server.
+  //    We don't want to be strictly cryptographically secure. The server might
+  //    reject the ID if there is a conflict or problem.
+  uint8 bytes[kInstanceIDByteLength];
+  crypto::RandBytes(bytes, sizeof(bytes));
+
+  // 2) Transforms the first 4 bits to 0x7. Note that this is required by the
+  //    server.
+  bytes[0] &= 0x0f;
+  bytes[0] |= 0x70;
+
+  // 3) Encode the value in Android-compatible base64 scheme:
+  //    * URL safe: '/' replaced by '_' and '+' replaced by '-'.
+  //    * No padding: any trailing '=' will be removed.
+  base::Base64Encode(
+      base::StringPiece(reinterpret_cast<const char*>(bytes), sizeof(bytes)),
+      &id_);
+  std::replace(id_.begin(), id_.end(), '+', '-');
+  std::replace(id_.begin(), id_.end(), '/', '_');
+  id_.erase(std::remove(id_.begin(), id_.end(), '='), id_.end());
+
+  creation_time_ = base::Time::Now();
+
+  // TODO(jianli):  Save the ID to the store.
 }
 
 }  // namespace instance_id