Explicitly set undefined virtual functions to = 0.

When compiling with coverage flags enabled, this class caused a missing
key function error at link-time.
[https://lld.llvm.org/missingkeyfunction]

The fix is to ensure that all non-pure, non-inline, virtual functions
are properly defined somewhere. Given the way this class is used, the
most appropriate response appears to be marking its member functions
as pure virtual.

Bug: 1049383
Change-Id: I2f4c063bb151ac409f41f12c6da6e7f71c0d2a4f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2040680
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739170}

chrome/browser/updates/update_notification_service_bridge.h

@@ -19,28 +19,28 @@ class UpdateNotificationServiceBridge {
   static std::unique_ptr<UpdateNotificationServiceBridge> Create();
 
   // Updates and persists |timestamp| in Android SharedPreferences.
-  virtual void UpdateLastShownTimeStamp(base::Time timestamp);
+  virtual void UpdateLastShownTimeStamp(base::Time timestamp) = 0;
 
   // Returns persisted timestamp of last shown notification from Android
   // SharedPreferences. Return nullopt if there is no data.
-  virtual base::Optional<base::Time> GetLastShownTimeStamp();
+  virtual base::Optional<base::Time> GetLastShownTimeStamp() = 0;
 
   // Updates and persists |interval| in Android SharedPreferences.
-  virtual void UpdateThrottleInterval(base::TimeDelta interval);
+  virtual void UpdateThrottleInterval(base::TimeDelta interval) = 0;
 
   // Returns persisted interval that might be throttled from Android
   // SharedPreferences. Return nullopt if there is no data.
-  virtual base::Optional<base::TimeDelta> GetThrottleInterval();
+  virtual base::Optional<base::TimeDelta> GetThrottleInterval() = 0;
 
   // Updates and persists |count| in Android SharedPreferences.
-  virtual void UpdateUserDismissCount(int count);
+  virtual void UpdateUserDismissCount(int count) = 0;
 
   // Returns persisted count from Android SharedPreferences.
-  virtual int GetUserDismissCount();
+  virtual int GetUserDismissCount() = 0;
 
   // Launches Chrome activity after user clicked the notification. Launching
   // behavior may be different which depends on |state|.
-  virtual void LaunchChromeActivity(int state);
+  virtual void LaunchChromeActivity(int state) = 0;
 
   virtual ~UpdateNotificationServiceBridge() = default;