Clear suggestions when language changes

When the language of the device is changed, the suggestions should be
displayed in the new language.
This CL clears the cached suggestions when the language is changed.

Bug: 765164
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I12894c18531c8d1771d6c7e0d2b6c558ba9ce110
Reviewed-on: https://chromium-review.googlesource.com/737631
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520109}

ios/chrome/app/main_controller.mm

@@ -32,6 +32,7 @@
 #include "components/feature_engagement/public/tracker.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/metrics/metrics_service.h"
+#include "components/ntp_snippets/content_suggestions_service.h"
 #include "components/payments/core/features.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "components/signin/core/browser/signin_manager.h"
@@ -83,6 +84,7 @@
 #include "ios/chrome/browser/metrics/first_user_action_recorder.h"
 #import "ios/chrome/browser/metrics/previous_session_info.h"
 #import "ios/chrome/browser/net/cookie_util.h"
+#include "ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.h"
 #include "ios/chrome/browser/payments/ios_payment_instrument_launcher.h"
 #include "ios/chrome/browser/payments/ios_payment_instrument_launcher_factory.h"
 #import "ios/chrome/browser/payments/payment_request_constants.h"
@@ -701,6 +703,12 @@ const int kExternalFilesCleanupDelaySeconds = 60;
 
   [MDCTypography setFontLoader:[MDFRobotoFontLoader sharedInstance]];
 
+  if ([PreviousSessionInfo sharedInstance].isFirstSessionAfterLanguageChange) {
+    IOSChromeContentSuggestionsServiceFactory::GetForBrowserState(
+        chromeBrowserState)
+        ->ClearAllCachedSuggestions();
+  }
+
   [self createInitialUI:(startInIncognito ? ApplicationMode::INCOGNITO
                                           : ApplicationMode::NORMAL)];
 

ios/chrome/browser/metrics/previous_session_info.h

@@ -26,6 +26,10 @@ extern NSString* const kDidSeeMemoryWarningShortlyBeforeTerminating;
 // Whether the app was updated between the previous and the current session.
 @property(nonatomic, assign, readonly) BOOL isFirstSessionAfterUpgrade;
 
+// Whether the language has been changed between the previous and the current
+// session.
+@property(nonatomic, assign, readonly) BOOL isFirstSessionAfterLanguageChange;
+
 // Singleton PreviousSessionInfo. During the lifetime of the app, the returned
 // object is the same, and describes the previous session, even after a new
 // session has started (by calling beginRecordingCurrentSession).

ios/chrome/browser/metrics/previous_session_info.mm

@@ -19,6 +19,10 @@ namespace {
 // last session.
 NSString* const kLastRanVersion = @"LastRanVersion";
 
+// Key in the NSUserDefaults for a string value that stores the language of the
+// last session.
+NSString* const kLastRanLanguage = @"LastRanLanguage";
+
 }  // namespace
 
 namespace previous_session_info_constants {
@@ -34,6 +38,7 @@ NSString* const kDidSeeMemoryWarningShortlyBeforeTerminating =
 // Redefined to be read-write.
 @property(nonatomic, assign) BOOL didSeeMemoryWarningShortlyBeforeTerminating;
 @property(nonatomic, assign) BOOL isFirstSessionAfterUpgrade;
+@property(nonatomic, assign) BOOL isFirstSessionAfterLanguageChange;
 
 @end
 
@@ -43,6 +48,8 @@ NSString* const kDidSeeMemoryWarningShortlyBeforeTerminating =
 @synthesize didSeeMemoryWarningShortlyBeforeTerminating =
     _didSeeMemoryWarningShortlyBeforeTerminating;
 @synthesize isFirstSessionAfterUpgrade = _isFirstSessionAfterUpgrade;
+@synthesize isFirstSessionAfterLanguageChange =
+    _isFirstSessionAfterLanguageChange;
 
 // Singleton PreviousSessionInfo.
 static PreviousSessionInfo* gSharedInstance = nil;
@@ -61,6 +68,11 @@ static PreviousSessionInfo* gSharedInstance = nil;
         base::SysUTF8ToNSString(version_info::GetVersionNumber());
     gSharedInstance.isFirstSessionAfterUpgrade =
         ![lastRanVersion isEqualToString:currentVersion];
+
+    NSString* lastRanLanguage = [defaults stringForKey:kLastRanLanguage];
+    NSString* currentLanguage = [[NSLocale preferredLanguages] objectAtIndex:0];
+    gSharedInstance.isFirstSessionAfterLanguageChange =
+        ![lastRanLanguage isEqualToString:currentLanguage];
   }
   return gSharedInstance;
 }
@@ -81,6 +93,10 @@ static PreviousSessionInfo* gSharedInstance = nil;
       base::SysUTF8ToNSString(version_info::GetVersionNumber());
   [defaults setObject:currentVersion forKey:kLastRanVersion];
 
+  // Set the new language.
+  NSString* currentLanguage = [[NSLocale preferredLanguages] objectAtIndex:0];
+  [defaults setObject:currentLanguage forKey:kLastRanLanguage];
+
   // Clear the memory warning flag.
   [defaults
       removeObjectForKey:previous_session_info_constants::

ios/chrome/browser/metrics/previous_session_info_unittest.mm

@@ -25,6 +25,9 @@ NSString* const kDidSeeMemoryWarningShortlyBeforeTerminating =
 // Key in the NSUserDefaults for a string value that stores the version of the
 // last session.
 NSString* const kLastRanVersion = @"LastRanVersion";
+// Key in the NSUserDefaults for a string value that stores the language of the
+// last session.
+NSString* const kLastRanLanguage = @"LastRanLanguage";
 
 using PreviousSessionInfoTest = PlatformTest;
 
@@ -33,6 +36,7 @@ TEST_F(PreviousSessionInfoTest, InitializationWithEmptyDefaults) {
   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
   [defaults removeObjectForKey:kDidSeeMemoryWarningShortlyBeforeTerminating];
   [defaults removeObjectForKey:kLastRanVersion];
+  [defaults removeObjectForKey:kLastRanLanguage];
 
   // Instantiate the PreviousSessionInfo sharedInstance.
   PreviousSessionInfo* sharedInstance = [PreviousSessionInfo sharedInstance];
@@ -40,6 +44,39 @@ TEST_F(PreviousSessionInfoTest, InitializationWithEmptyDefaults) {
   // Checks the default values.
   EXPECT_FALSE([sharedInstance didSeeMemoryWarningShortlyBeforeTerminating]);
   EXPECT_TRUE([sharedInstance isFirstSessionAfterUpgrade]);
+  EXPECT_TRUE([sharedInstance isFirstSessionAfterLanguageChange]);
+}
+
+TEST_F(PreviousSessionInfoTest, InitializationWithSameLanguage) {
+  [PreviousSessionInfo resetSharedInstanceForTesting];
+  NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
+  [defaults removeObjectForKey:kLastRanLanguage];
+
+  // Set the current language as the last ran language.
+  NSString* currentVersion = [[NSLocale preferredLanguages] objectAtIndex:0];
+  [defaults setObject:currentVersion forKey:kLastRanVersion];
+
+  // Instantiate the PreviousSessionInfo sharedInstance.
+  PreviousSessionInfo* sharedInstance = [PreviousSessionInfo sharedInstance];
+
+  // Checks the values.
+  EXPECT_TRUE([sharedInstance isFirstSessionAfterLanguageChange]);
+}
+
+TEST_F(PreviousSessionInfoTest, InitializationWithDifferentLanguage) {
+  [PreviousSessionInfo resetSharedInstanceForTesting];
+  NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
+  [defaults removeObjectForKey:kLastRanLanguage];
+
+  // Set the current language as the last ran language.
+  NSString* currentVersion = @"Fake Language";
+  [defaults setObject:currentVersion forKey:kLastRanVersion];
+
+  // Instantiate the PreviousSessionInfo sharedInstance.
+  PreviousSessionInfo* sharedInstance = [PreviousSessionInfo sharedInstance];
+
+  // Checks the values.
+  EXPECT_TRUE([sharedInstance isFirstSessionAfterLanguageChange]);
 }
 
 TEST_F(PreviousSessionInfoTest, InitializationWithSameVersionNoMemoryWarning) {