Upstream JavaScript injection for iOS

ios/web/web_state/js/crw_js_injection_manager.mm

+// Copyright 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/web/public/web_state/js/crw_js_injection_manager.h"
+
+#import <UIKit/UIKit.h>
+
+#include "base/logging.h"
+#include "base/mac/bundle_locations.h"
+#import "base/mac/scoped_nsobject.h"
+#include "base/strings/sys_string_conversions.h"
+#import "ios/web/public/web_state/js/crw_js_injection_receiver.h"
+
+namespace {
+// Template with presence beacon check to prevent re-injection of JavaScript.
+NSString* const kPresenceCheckTemplate = @"if (typeof %@ !== 'object') { %@ }";
+}
+
+@implementation CRWJSInjectionManager {
+  // JS to inject into the page. This may be nil if it has been purged due to
+  // low memory.
+  base::scoped_nsobject<NSString> _injectObject;
+  // An object the can receive JavaScript injection.
+  CRWJSInjectionReceiver* _receiver;  // Weak.
+}
+
+- (id)initWithReceiver:(CRWJSInjectionReceiver*)receiver {
+  DCHECK(receiver);
+  self = [super init];
+  if (self) {
+    _receiver = receiver;
+    // Register for low-memory warnings.
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(lowMemoryWarning:)
+               name:UIApplicationDidReceiveMemoryWarningNotification
+             object:nil];
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [super dealloc];
+}
+
+- (BOOL)hasBeenInjected {
+  DCHECK(self.presenceBeacon);
+  return [_receiver scriptHasBeenInjectedForClass:[self class]
+                                   presenceBeacon:self.presenceBeacon];
+}
+
+- (void)inject {
+  if ([self hasBeenInjected])
+    return;
+  [self injectDependenciesIfMissing];
+  [_receiver injectScript:[self injectionContent] forClass:[self class]];
+  DCHECK([self hasBeenInjected]);
+}
+
+- (NSString*)injectionContentIncludingDependencies {
+  NSArray* allDependencies = [self allDependencies];
+  NSMutableArray* scripts =
+      [NSMutableArray arrayWithCapacity:allDependencies.count];
+  for (CRWJSInjectionManager* dependency in allDependencies) {
+    [scripts addObject:[dependency injectionContent]];
+  }
+  NSString* script = [scripts componentsJoinedByString:@""];
+  NSString* beacon = [self presenceBeacon];
+  return [NSString stringWithFormat:kPresenceCheckTemplate, beacon, script];
+}
+
+- (void)lowMemoryWarning:(NSNotification*)notify {
+  _injectObject.reset();
+}
+
+- (void)deferredEvaluate:(NSString*)script {
+  NSString* deferredScript = [NSString
+      stringWithFormat:@"window.setTimeout(function() {%@}, 0)", script];
+  [self evaluate:deferredScript stringResultHandler:nil];
+}
+
+- (void)evaluate:(NSString*)script
+    stringResultHandler:(web::JavaScriptCompletion)completionHandler {
+  [_receiver evaluateJavaScript:script stringResultHandler:completionHandler];
+}
+
+- (NSArray*)directDependencies {
+  return @[];
+}
+
+- (NSArray*)allDependencies {
+  NSMutableArray* allDendencies = [NSMutableArray array];
+  for (Class dependencyClass in [self directDependencies]) {
+    CRWJSInjectionManager* dependency =
+        [_receiver instanceOfClass:dependencyClass];
+    NSArray* list = [dependency allDependencies];
+    for (CRWJSInjectionManager* manager in list) {
+      if (![allDendencies containsObject:manager])
+        [allDendencies addObject:manager];
+    }
+  }
+  [allDendencies addObject:self];
+  return allDendencies;
+}
+
+#pragma mark -
+#pragma mark ProtectedMethods
+
+- (CRWJSInjectionReceiver*)receiver {
+  return _receiver;
+}
+
+- (NSString*)scriptPath {
+  NOTREACHED();
+  return nil;
+}
+
+- (NSString*)presenceBeacon {
+  return nil;
+}
+
+- (NSString*)injectionContent {
+  if (!_injectObject)
+    _injectObject.reset([[self staticInjectionContent] copy]);
+  return _injectObject.get();
+}
+
+- (NSString*)staticInjectionContent {
+  DCHECK(self.scriptPath);
+  NSString* path = [base::mac::FrameworkBundle() pathForResource:self.scriptPath
+                                                          ofType:@"js"];
+  DCHECK(path) << "Script file not found: "
+               << base::SysNSStringToUTF8(self.scriptPath) << ".js";
+  NSError* error = nil;
+  NSString* content = [NSString stringWithContentsOfFile:path
+                                                encoding:NSUTF8StringEncoding
+                                                   error:&error];
+  DCHECK(!error) << "Error fetching script: " << [error.description UTF8String];
+  DCHECK(content);
+  return content;
+}
+
+- (void)injectDependenciesIfMissing {
+  for (Class dependencyClass in [self directDependencies]) {
+    CRWJSInjectionManager* dependency =
+        [_receiver instanceOfClass:dependencyClass];
+    [dependency inject];
+  }
+}
+
+@end